High sensitivity of middle-wavelength infrared photodetectors based on an individual InSb nanowire
© Kuo et al.; licensee Springer. 2013
Received: 2 April 2013
Accepted: 11 July 2013
Published: 18 July 2013
Single-crystal indium antimony (InSb) nanowire was fabricated into middle-infrared photodetectors based on a metal–semiconductor-metal (M-S-M) structure. The InSb nanowires were synthesized using an electrochemical method at room temperature. The characteristics of the FET reveal an electron concentration of 3.6 × 1017 cm−3 and an electron mobility of 215.25 cm2 V−1 s−1. The photodetectors exhibit good photoconductive performance, excellent stability, reproducibility, superior responsivity (8.4 × 104 A W−1), and quantum efficiency (1.96 × 106%). These superior properties are attributed to the high surface-to-volume ratio and single-crystal 1D nanostructure of photodetectors that significantly reduce the scattering, trapping, and the transit time between the electrodes during the transport process. Furthermore, the M-S-M structure can effectively enhance space charge effect by the formation of the Schottky contacts, which significantly assists with the electron injection and photocurrent gain.
KeywordsElectrochemical method InSb nanowires Middle-infrared Photodetectors Metal–semiconductor-metal structure
One-dimensional (1D) nanostructure materials have received considerable attention because of their importance in potential applications in electronics and photoelectric nanodevices . With high surface-to-volume ratio and Debye lengths comparable to nanomaterial's diameters, the electronic and photoelectric properties of 1D nanostructure are strongly affected by the surface effect via chemisorption (oxygen adsorption) and native surface defects [2–4]. Thus, 1D nanostructure exhibits a superior sensitivity to light and chemical molecules compared to the thin film and bulk. Due to these properties, electronic devices fabricated using 1D nanostructure have been extensively adapted in photodetectors , gas sensors , and dye-sensitized solar cells , respectively. Of these application fields, photodetectors or switches based on semiconductor materials have been the focus of considerable attention in recent years because of their high sensitivity and high quantum efficiency. Furthermore, the different energy band gaps imply that photodetectors can be applied flexibly on various wavelengths. To date, photodetectors based on 1D semiconductor nanostructures, such as SnO2 nanowires , ZnO nanowires , ZnSe nanobelts , CdS nanoribbons , and CuO nanowires , have been reported. These 1D nanostructure photodetectors exhibit outstanding performance; however, the detection range that has been investigated so far falls primarily between the infrared and ultraviolet region. In fact, 1D nanostructure photodetectors of the mid- to long-wavelength infrared (IR) region have seldom been reported because only a few other materials can be used in this region.
Indium antimony (InSb), one of the III-V compounds with a face-centered cubic structure of the zincblende type, is a useful material for producing mid- to long-wavelength IR photodetectors because of the smallest band gap (Eg = 0.17 eV, at 300 K). In addition, owing to the small effective mass (m*e = 0.014 mo) and the ballistic length (up to 0.7 μm at 300 K), InSb has an extremely high carrier mobility (i.e., electron mobility of 77,000 cm2V-1s-1) . Therefore, InSb is a highly promising material for device applications involving high-speed-response electronic nanodevices, optical communication devices, and optical detectors [13, 14]. Owing to the aforementioned unique characteristics, now, many groups use different synthesis methods to produce InSb nanowires, i.e., chemical beam epitaxy , chemical vapor deposition , and pulsed laser deposition (PLD) . Meanwhile, the electrical transport characteristics are also widely investigated [18, 19]. However, only few groups study on the IR detectors, particularly on the mid- to long-wavelength region [20, 21]. This work shows that InSb nanowires can be successfully synthesized at room temperature by applying electrochemical method with an anodic aluminum oxide (AAO) template. The synthesizing process was simple, fast, and straightforward in fabricating large-area InSb nanowires at low temperature compared to other thermal reactive processes. Moreover, individual InSb nanowires based on a metal–semiconductor-metal (M-S-M) structure were fabricated into the photodetectors. It shows high sensitivity, good stability, reproducibility, and response speed after illumination with middle-infrared (M-IR; 5.5 μm) light. Furthermore, a systematic study of the photoresponse was performed, which revealed a clear dependence of the photocurrent, carrier lifetime, and quantum efficiency on the light intensity, defect, and M-S-M structure.
InSb nanowires were synthesized using the electrochemical method. A gold (Au) film coated on an AAO (Whatman®, GE Healthcare, Maidstone, UK) membrane was used as a conductive layer to grow the nanowires. The pore diameter of the AAO membrane was approximately 200 nm. The electrolyte consisted of 0.15 M InCl3, 0.1 M SbCl3, 0.36 M C6H8O7·H2O, and 0.17 M KCl. The solvent of the electrolyte was distilled water. A typical three-electrode electrochemical cell was used during the InSb electrodeposition. The Au film on the AAO membrane was regarded as the working electrode. A platinum wire and an Ag/AgCl electrode were subsequently applied as the counter electrode and the reference electrode, respectively. The deposition time was controlled at 40 min in conditions of a deposition potential of −1.5 V, in contrast to the Ag/AgCl reference electrode at room temperature. Following the deposition, the sample was removed from the AAO membrane with a 5 wt % NaOH solution and then washed five times with distilled water.
The as-prepared nanowires were examined using field emission scanning electron microscope (FESEM; operated at 10 kV; HITACHI S-4800, Chiyoda-ku, Japan), a desktop X-ray diffractometer (D2 Phaser, Bruker, Madison, WI, USA), a high-resolution transmission electron microscope (HRTEM; operated at 200 kV, JEM-2100F, JEOL Ltd., Tokyo, Japan) with energy-dispersive X-ray spectroscope (EDX), and an X-ray photoelectron spectroscope system (PHI600 system, PerkinElmer, Waltham, MA, USA). Furthermore, the transport property was evaluated using the InSb nanowires further fabricated into a field-effect transistor (FET). The synthesized InSb nanowires were dispersed uniformly in ethanol and dropped on a SiO2/p-Si substrate. The Si substrate was applied as a back-gate. After drying out the suspension, the Ti/Cu (20/120 nm) electrodes were deposited on the two ends of the nanowire through photolithograph, e-beam evaporation, and lift-off processes. Additionally, the InSb nanowire-based M-S-M structure photodetectors were fabricated through a microfabrication process and focused ion beam (FIB) technique. Here, the pattern of Ti/Au (20/120 nm) electrode was fabricated using standard lithographic methods on a SiO2/Si substrate. The synthesized InSb nanowires were transferred onto a SiO2/Si substrate with pre-patterned Ti/Au electrodes. Subsequently, the FIB instrument (Dual-Beam Helios 600i, FEI, Shanghai, China) was used to deposit Pt, which connects the wires between the Ti/Au electrodes. Finally, The Pt-InSb-Pt (M-S-M) photodetector structure of back-to-back Schottky contacts was obtained. To evaluate the M-S-M photodetectors, a M-IR light at a 5.5-μm wavelength was used as an excitation light source. The transport and photosensitivity properties were analyzed using the semiconductor characterization system (4200-SCS, Keithley Instruments Inc., Cleveland, OH, USA) at room temperature.
Results and discussion
The negative Gibbs energy (Δ G) implies that the formation reaction is spontaneous. Equation (1) demonstrates the feasibility of applying the electrochemical method to synthesize the InSb nanowires at room temperature.
This work finds that Rλ and QE decrease with increasing light intensity. The reductions of Rλ and QE are strong manifestations of a hole trap at a relatively high light intensity. Under illumination, the photogenerated holes were trapped by the oxygen ions, and the electrons contributed to the photocurrent. However, the saturation of the electron is trap at high light intensity, reducing the number of available hole traps because of the increasing recombination of photogenerated electron–hole pairs [38, 42]. Furthermore, the onset of electron–hole pair recombination at a high light intensity might also contribute to the shortening of the carrier lifetime.
In this work, the high QE for the InSb nanowires is ascribed to the high surface-to-volume ratio and superior crystallinity of the InSb nanowires and the M-S-M structure. The high surface-to-volume ratio can significantly increase the number of hole-trap states and prolong the carrier lifetime. In the dark, oxygen molecules are adsorbed on the nanowire surface and capture free electrons (O2(g) + e− → O2−(ad)), and thus, the depletion layer forms near the surface, which reduces the density and mobility of the carrier. When illuminated (hν → e− + h+), electron–hole pairs are generated; the holes migrate to the surface and discharge the adsorbed oxygen ions through an electron–hole recombination (h+ + O2−(ad) →O2(g)). Unpaired electrons become major carriers that contribute to the photocurrent. This hole-trapping process significantly separates the electron–hole pairs and largely increases the carrier lifetime. [3, 4, 47] Meanwhile, the superior crystallinity of InSb nanowires can reduce the scattering and carrier trapping during the transport process between two electrodes, and the photocurrent rapidly reaches a steady state in both the response and the recovery stages .
This work demonstrated the feasibility of synthesizing single-crystal InSb nanowires using the electrochemical method at room temperature. Characteristic FET devices based on InSb nanowires have n-type conductivity because of the Sb vacancies. Meanwhile, InSb nanowires have an electron concentration of 3.6× 1017 cm−3 and an electron mobility of 215.25 cm2 V−1 s−1. Individual InSb nanowire was fabricated for M-IR photodetectors based on the M-S-M structure. A power-law dependence of the photocurrent on the light intensity was observed, which suggests the existence of defect states that are consistent with an n-type conductivity mechanism in the InSb nanowires. Moreover, the photodetectors exhibit good photoconductive performance, good stability and reproducibility, superior responsivity (8.4 × 104 A W−1), and quantum efficiency (1.96 × 106%). These unique properties are attributed to the high surface-to-volume ratio and superior crystallinity of InSb nanowires. In addition, the M-S-M structure can further enhance Ne (or ΔI) and the electron transport speed, significantly increasing the sensitivity of the photodetectors. The superior photoelectric properties of InSb nanowires are highly promising for application in high-sensitivity and high-speed nanoscale optical communication devices and photodetectors.
CHK and WCC are PhD students at National Tsing Hua University. SJL holds a professor position at National Tsing Hua University. JMW holds an associate professor position at National Tsing Hua University.
The authors thank Mr. Guo-Kai Hsu for the helpful SEM analyses, Mr. Hsin-I Lin for the helpful FIB experiment, and the financial supports from the National Science Council, Taiwan, under grant numbers NSC-99-2221-E-007-069-MY3 and NSC-100-2628-E-035-006-MY2.
- Chen CY, Huang JH, Lai KY, Jen YJ, Liu CP, He JH: Giant optical anisotropy of oblique-aligned ZnO nanowire arrays. Opt Express 2012, 20: 2015–2024. 10.1364/OE.20.002015View Article
- Chen MW, Chen CY, Lien DH, Ding Y, He JH: Photoconductive enhancement of single ZnO nanowire through localized Schottky effects. Opt Express 2010, 18: 14836–14841. 10.1364/OE.18.014836View Article
- Chen CY, Chen MW, Ke JJ, Lin CA, Retamal JRD, He JH: Surface effects on optical and electrical properties of ZnO nanostructures. Pure Appl Chem 2010, 82: 2055–2073. 10.1351/PAC-CON-09-12-05View Article
- Chen CY, Retamal JRD, Wu IW, Lien DH, Chen MW, Ding Y, Chueh YL, Wu CI, He JH: Probing surface band bending of surface-engineered metal oxide nanowires. ACS Nano 2012, 6: 9366–9372. 10.1021/nn205097eView Article
- Li L, Auer E, Liao M, Fang X, Zhai T, Gautam UK, Lugstein A, Koide Y, Bandoa Y, Golberg D: Deep-ultraviolet solar-blind photoconductivity of individual gallium oxide nanobelts. Nanoscale 2011, 3: 1120–1126. 10.1039/c0nr00702aView Article
- Wu JM: A room temperature ethanol sensor made from p-type Sb-doped SnO2 nanowires. Nanotechnology 2010, 21: 235501. 10.1088/0957-4484/21/23/235501View Article
- Liu M, Wang H, Yan C, Will G, Bell J: One-step synthesis of titanium oxide with trilayer structure for dye-sensitized solar cells. Appl Phys Lett 2011, 98: 133113. 10.1063/1.3573799View Article
- Wu JM, Kuo CH: Ultraviolet photodetectors made from SnO2 nanowires. Thin Solid Films 2009, 517: 3870–3873. 10.1016/j.tsf.2009.01.120View Article
- Kind H, Yan H, Messer B, Law M, Yang P: Nanowire ultraviolet photodetectors and optical switches. Adv Mater 2002, 14: 158–160. 10.1002/1521-4095(20020116)14:2<158::AID-ADMA158>3.0.CO;2-WView Article
- Fang X, Xiong S, Zhai T, Bando Y, Liao M, Gautam UK, Koide Y, Zhang X, Qian Y, Golberg D: High-performance blue/ultraviolet-light-sensitive ZnSe-nanobelt photodetectors. Adv Mater 2009, 21: 5016–5502. 10.1002/adma.200902126View Article
- Jie JS, Zhang WJ, Jiang Y, Meng XM, Li YQ, Lee ST: Photoconductive characteristics of single-crystal CdS nanoribbons. Nano Lett 2006, 6: 1887–1892. 10.1021/nl060867gView Article
- Wang SB, Hsiao CH, Chang SJ, Lam KT, Wen KH, Hung SC, Young SJ, Huang BR: A CuO nanowire infrared photodetector. Sensor Actuat A-Phys 2011, 171: 207–211. 10.1016/j.sna.2011.09.011View Article
- Rode DL: Electron transport in InSb, InAs, and InP. Phys Rev B 1971, 3: 3287–3299. 10.1103/PhysRevB.3.3287View Article
- Zhang XR, Hao YF, Meng GW, Zhang LD: Fabrication of highly ordered InSb nanowire arrays by electrodeposition in porous anodic alumina membranes. J Electrochem Soc 2005, 152: C664-C668. 10.1149/1.2007187View Article
- Vogel AT, Boor J, Becker M, Wittemann JV, Mensah SL, Werner P, Schmidt V: Ag-assisted CBE growth of ordered InSb nanowire arrays. Nanotechnology 2011, 22: 015605. 10.1088/0957-4484/22/1/015605View Article
- Vaddiraju S, Sunkara MK, Chin AH, Ning CZ, Dholakia GR, Meyyappan M: Synthesis of group III antimonide nanowires. J Phys Chem C 2007, 111: 7339–7347. 10.1021/jp068943rView Article
- Wang YN, Chi JH, Banerjee K, Grützmacher D, Schäpers T, Lu JG: Field effect transistor based on single crystalline InSb nanowire. J Mater Chem 2011, 21: 2459–2462. 10.1039/c0jm03855eView Article
- Caroff P, Wagner JB, Dick KA, Nilsson HA, Jeppsson M, Deppert K, Samuelson L, Wallenberg LR, Wernersson LE: High-quality InAs/InSb nanowire heterostructures grown by metal–organic vapor-phase epitaxy. Small 2008, 4: 878–882. 10.1002/smll.200700892View Article
- Nilsson HA, Caroff P, Thelander C, Lind E, Karlström O, Wernersson LE: Temperature dependent properties of InSb and InAs nanowire field-effect transistors. Appl Phys Lett 2010, 96(153505):1–3.
- Svensson J, Anttu N, Vainorius N, Borg BM, Wernersson LE: Diameter-dependent photocurrent in InAsSb nanowire infrared photodetectors. Nano Lett 2013, 13: 1380–1385.
- Chen H, Sun X, Lai KWC, Meyyappan M, Xi N: Infrared detection using an InSb nanowire. In Proceedings of IEEE Nanotechnology Materials and Devices Conference: June 2–5 2009; Traverse City, Mi, USA. New York: IEEE; 2009:212–216.View Article
- Jin YJ, Zhang DH, Chen XZ, Tang XH: Sb antisite defects in InSb epilayers prepared by metalorganic chemical vapor deposition. J Cryst Growth 2011, 318: 356–359. 10.1016/j.jcrysgro.2010.10.105View Article
- Rahul , Vishwakarma SR, Verma AK, Tripathi RSN: Energy band gap and conductivity measurement of InSb thin films deposited by electron beam evaporation technique. M J Condensed Matter 2010, 13: 34–37.
- Vishwakarma SR, Verma AK, Tripathi RSN, Das S, Rahul : Study of structural property of n-type indium antimonide thin films. Indian J Pure and Appl Phys 2012, 50: 339–346.
- Kuo CH, Wu JM, Lin SJ: Room temperature-synthesized vertically aligned InSb nanowires: electrical transport and field emission characteristics. Nanoscale Res Lett 2013, 8: 69. 10.1186/1556-276X-8-69View Article
- Lim T, Lee S, Meyyappan M, Ju S: Tin oxide and indium oxide nanowire transport characteristics: influence of oxygen concentration during synthesis. Semicond Sci Technol 2012, 27: 035018. 10.1088/0268-1242/27/3/035018View Article
- Stern E, Cheng G, Cimpoiasu E, Klie R, Guthrie S, Klemic J, Kretzschma I, Steinlauf E, Turner-Evans D, Broomfield E, Hyland J, Koudelka R, Boone T, Young M, Sanders A, Munden R, Lee T, Routenberg D, Reed MA: Electrical characterization of single GaN nanowires. Nanotechnology 2005, 16: 2941–2953. 10.1088/0957-4484/16/12/037View Article
- Yuan GD, Zhang WJ, Jie JS, Fan X, Zapien JA, Leung YH, Luo LB, Wang PF, Lee CS, Lee ST: p-type ZnO nanowire arrays. Nano Lett 2008, 8: 8.
- Thelander C, Caroff P, Plissard S, Dick KA: Electrical properties of InAs1−xSb x and InSb nanowires grown by molecular beam epitaxy. Appl Phys Lett 2012, 100: 232105–1. 10.1063/1.4726037View Article
- Das SR, Delker CJ, Zakharov D, Chen YP, Sands TD, Janes DB: Room temperature device performance of electrodeposited InSb nanowire field effect transistors. Appl Phys Lett 2011, 98: 243504–1. 10.1063/1.3587638View Article
- Plissard SR, Slapak DR, Verheijen MA, Hocevar M, Immink GWG, Weperen I, Nadj-Perge S, Frolov SM, Kouwenhoven LP, Bakkers EPAM: From InSb nanowires to nanocubes: looking for the sweet spot. Nano Lett 2012, 12: 1794–1798. 10.1021/nl203846gView Article
- Khanal DR, Levander AX, Yu KM, Liliental-Weber Z, Walukiewicz W, Grandal J, Sánchez-García MA, Calleja E, Wu J: Decoupling single nanowire mobilities limited by surface scattering and bulk impurity scattering. Appl Phys Lett 2011, 110: 033705.9.
- Wu JM, Liou LB: Room temperature photo-induced phase transitions of VO2 nanodevices. J Mater Chem 2011, 21: 5499–5504. 10.1039/c0jm03203dView Article
- Luo LB, Liang X, Jie JS: Sn-catalyzed synthesis of SnO2 nanowires and their optoelectronic characteristics. Nanotechnology 2011, 22: 485701. 10.1088/0957-4484/22/48/485701View Article
- Chang LW, Sung YC, Yeh JW, Shih HC: Enhanced optoelectronic performance from the Ti-doped ZnO nanowires. J Appl Phys 2011, 109: 074318. 10.1063/1.3554686View Article
- Li L, Lee PS, Yan C, Zhai T, Fang X, Liao M, Koide Y, Bando Y, Golberg D: Ultrahigh-performance solar-blind photodetectors based on individual single-crystalline In2Ge2O7 nanobelts. Adv Mater 2010, 22: 5145–5149. 10.1002/adma.201002608View Article
- Li QH, Gao T, Wang TH: Optoelectronic characteristics of single CdS nanobelts. Appl Phys Lett 2005, 86: 193109. 10.1063/1.1923186View Article
- Xie X, Kwok SY, Lu Z, Liu Y, Cao Y, Luo L, Zapien JA, Bello I, Lee CS, Lee ST, Zhang W: Visible–NIR photodetectors based on CdTe nanoribbons. Nanoscale 2012, 4: 2914–2919. 10.1039/c2nr30277bView Article
- Li L, Fang X, Zhai T, Liao M, Gautam UK, Wu X, Koide Y, Bando Y, Golberg D: Electrical transport and high-performance photoconductivity in individual ZrS2 nanobelts. Adv Mater 2010, 22: 4151–4156. 10.1002/adma.201001413View Article
- Liang Y, Liang H, Xiao X, Hark S: The epitaxial growth of ZnS nanowire arrays and their applications in UV-light detection. J Mater Chem 2012, 22: 1199. 10.1039/c1jm13903gView Article
- Zhang C, Wang S, Yang L, Liu Y, Xu T, Ning Z, Zak A, Zhang Z, Tenne R, Chen Q: High-performance photodetectors for visible and near-infrared lights based on individual WS2 nanotubes. Appl Phys Lett 2012, 100: 243101. 10.1063/1.4729144View Article
- Binet F, Duboz JY, Rosencher E, Scholz F, Härle V: Mechanisms of recombination in GaN photodetectors. Appl Phys Lett 1996, 69: 1202. 10.1063/1.117411View Article
- Jie J, Zhang W, Bello I, Lee CS, Lee ST: One-dimensional II–VI nanostructures: synthesis, properties and optoelectronic applications. Nano Today 2010, 5: 313–336. 10.1016/j.nantod.2010.06.009View Article
- Jiang Y, Zhang WJ, Jie JS, Meng XM, Fan X, Lee ST: Photoresponse properties of CdSe single-nanoribbon photodetectors. Adv Funct Mater 2007, 17: 1795–1800. 10.1002/adfm.200600351View Article
- Li QH, Gao T, Wang YG, Wang TH: Adsorption and desorption of oxygen probed from ZnO nanowire films by photocurrent measurements. Appl Phys Lett 2005, 86: 123117. 10.1063/1.1883711View Article
- Wu JM, Chen YR, Lin YH: Rapidly synthesized ZnO nanowires by ultraviolet decomposition process in ambient air for flexible photodetector. Nanoscale 2011, 3: 1053–1058. 10.1039/c0nr00595aView Article
- Hasan K, Alvil NH, Lu J, Nur O, Willander M: Single nanowire-based UV photodetectors for fast switching. Nanoscale Res Lett 2011, 6: 348. 10.1186/1556-276X-6-348View Article
- Zhang J, Chen R, Xu X, Li D, Sun H, Xiong Q: Synthesis and optical properties of II–VI 1D nanostructures. Nanoscale 2012, 4: 1422. 10.1039/c1nr11612fView Article
- Li C, Bando Y, Liao M, Koide Y, Golberg D: Visible-blind deep-ultraviolet Schottky photodetector with a photocurrent gain based on individual Zn2GeO4 nanowire. Appl Phys Lett 2010, 97: 161102. 10.1063/1.3491212View Article
- Das SN, Moon KJ, Kar JP, Choi JH, Xiong J, Lee TI, Myoung JM: ZnO single nanowire-based UV detectors. Appl Phys Lett 2010, 97: 022103. 10.1063/1.3464287View Article
- Hu Y, Zhou J, Yeh PH, Li Z, Wei TY, Wang ZL: Supersensitive, fast-response nanowire sensors by using Schottky contacts. Adv Mater 2010, 22: 3327–3332. 10.1002/adma.201000278View Article
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