InGaAs Quantum Well Grown on High-Index Surfaces for Superluminescent Diode Applications
© The Author(s) 2010
Received: 12 January 2010
Accepted: 6 April 2010
Published: 22 April 2010
The morphological and optical properties of In0.2Ga0.8As/GaAs quantum wells grown on various substrates are investigated for possible application to superluminescent diodes. The In0.2Ga0.8As/GaAs quantum wells are grown by molecular beam epitaxy on GaAs (100), (210), (311), and (731) substrates. A broad photoluminescence emission peak (~950 nm) with a full width at half maximum (FWHM) of 48 nm is obtained from the sample grown on (210) substrate at room temperature, which is over four times wider than the quantum well simultaneously grown on (100) substrate. On the other hand, a very narrow photoluminescence spectrum is observed from the sample grown on (311) with FWHM = 7.8 nm. The results presented in this article demonstrate the potential of high-index GaAs substrates for superluminescent diode applications.
KeywordsPhotoluminescence Quantum well High-index surfaces Superluminescent diode Atomic force microscopy
Superluminescent diodes (SLDs) have been of great interest due to various applications, such as optical coherence tomography (OCT) and optical sensors [1, 2]. Significant research efforts have been focused upon increasing the spectral bandwidth as broadband SLDs are expected to improve depth resolutions for OCT systems [1–4]. A variety of approaches have been used to broaden the spectral bandwidth by engineering the device active regions through including quantum dots , multiple quantum wells (MQWs) , stacked twin active layers , asymmetric dual quantum wells , and quantum-well intermixing .
Among the many attempts in broadening the spectral width, there have been surprisingly few, if any, efforts made on high-index substrates based SLDs. Due to the difference in growth kinetic, strain, charge or surface polarity, as well as band structures on high-index surfaces [8–12], semiconductor quantum structures on these surfaces have been showing interesting phenomena [13–16]. For example, lateral ordering of QDs and QD clusters have been observed on B-type high-index surfaces and (731) surface, respectively [17, 18]. Even though intensive research efforts and significant progresses have been made on the high-index GaAs surfaces, there is a lack of research on high-indexed substrate for superluminescent diodes.
Accordingly, this work focuses on the effects of surface orientation on morphological and optical properties as well as explores the possibility of high-index surfaces for SLD applications. It has been well known that different substrate orientations have different growth reaction kinetics as well as various microscopic patterning of the surface . The latter property, natural roughness, presents on the high-index substrates influence the structure electronic properties and hence providing an additional means of emission spectrum broadening . Therefore, high-index surfaces may help advance the state of the art in SLDs in broadening emission spectrum. In this article, GaAs (100)-, (210)-, (311)-, and (731)-oriented substrates are used in this study.
The In0.2Ga0.8As/GaAs quantum well structures under investigation are grown simultaneously on epi-ready GaAs substrates by a solid-source molecular beam epitaxy (MBE) 32P Riber system. In this work, four substrates (100), (210), (311), and (731) are chosen and mounted side by side on a same molybdenum block. An important point to mention here is that the growth conditions are optimized only for (100)-oriented substrate. After oxide desorption at 600°C, a GaAs buffer layer of 500 nm is grown at substrate temperature of 580°C. The GaAs growth rate is one monolayer (ML) per second. Sequentially, 400-nm GaAs was grown at 0.7 ML/s, followed by 50 nm Al0.3Ga0.7As layer. The active region consists of only one In0.2Ga0.8As quantum well of 7 nm grown at 520°C, sandwiched by 50 nm barriers of GaAs. Another 50-nm Al0.3Ga0.7As layer is grown following the growth of the GaAs barrier. In the end, the entire growth is finished by another layer of 50 nm GaAs, and an additional 7-nm In0.2Ga0.8As is deposited on the surface for morphology study. All samples are not doped to eliminate the doping effects on optical properties of different oriented planes. Morphology study is carried out by an atomic force microscopy (AFM). The optical properties of all samples are studied by photoluminescence (PL) technique from 77 to 295 K. The excitation wavelength and power is 532 nm and 50 mW, respectively.
Results and Discussion
FWHM values of In0.2Ga0.8As/GaAs PL spectra on all orientations, and energy shift ∆E (= E(100) − E(xyz)) for high-index surfaces compared to (100)
In conclusion, the morphology of In0.2Ga0.8As/GaAs grown on GaAs (100), (210), (311), and (731) substrates has been studied by AFM. Three-dimensional nanostructure has been observed for (210)- and (311)-oriented surfaced. Moreover, the optical properties of the samples have been investigated by PL measurement. Spectral broadening has been observed for sample grown on (210) surface. The results presented in this work suggest future potential of high-index surfaces for superluminescent diode applications.
This work was supported by the Arkansas Biosciences Institute and the MRSEC Program of NSF Grant No. (DMR-0520550).
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
- Zhang ZY, Jiang Q, Luxmoore IJ, Hogg RA: A p-type-doped quantum dot superluminescent LED with broadband and flat-topped emission spectra obtained by post-growth intermixing under a GaAs proximity cap. Nanotechnology 2009,20(5):55204. COI number [1:STN:280:DC%2BD1MzitlOhtA%3D%3D]; Bibcode number [2009Nanot..20E5204Z] COI number [1:STN:280:DC%2BD1MzitlOhtA%3D%3D]; Bibcode number [2009Nanot..20E5204Z] 10.1088/0957-4484/20/5/055204View Article
- Wang J, Hamp MJ, Cassidy DT: Design considerations for asymmetric multiple quantum well broad spectral width superluminescent diodes. IEEE J. Quantum Electron. 2008, 44: 1256–1262. COI number [1:CAS:528:DC%2BD1cXhsV2rsLnM]; Bibcode number [2008IJQE...44.1256W] COI number [1:CAS:528:DC%2BD1cXhsV2rsLnM]; Bibcode number [2008IJQE...44.1256W] 10.1109/JQE.2008.2003104View Article
- Xin Y-C, Martinez A, Saiz T, Moscho AJ, Li Y, Nilsen TA, Gray AL, Lester LF: 1.3-μm quantum-dot multisection superluminescent diodes with extremely broad bandwidth. IEEE Photon. Technol. Lett. 2007, 19: 501–503. Bibcode number [2007IPTL...19..501X] Bibcode number [2007IPTL...19..501X] 10.1109/LPT.2007.893567View Article
- Zhang ZY, Hogg RA, Xu B, Jin P, Wang ZG: Realization of extremely broadband quantum-dot superluminescent light-emitting diodes by rapid thermal-annealing process. Opt. Lett. 2008, 33: 1210. COI number [1:STN:280:DC%2BD1czltFGnsg%3D%3D]; Bibcode number [2008OptL...33.1210Z] COI number [1:STN:280:DC%2BD1czltFGnsg%3D%3D]; Bibcode number [2008OptL...33.1210Z] 10.1364/OL.33.001210View Article
- Mikami O, Yasaka H, Noguchi Y: Broader spectral width InGaAsP stacked active layer superluminescent diodes. Appl. Phys. Lett. 1990, 56: 987–989. COI number [1:CAS:528:DyaK3cXhs1yksbY%3D]; Bibcode number [1990ApPhL..56..987M] COI number [1:CAS:528:DyaK3cXhs1yksbY%3D]; Bibcode number [1990ApPhL..56..987M] 10.1063/1.102571View Article
- Andreeva EV, Volkov NA, Kostin YO, Lapin PI, Marmalyuk AA, Sabitov DR, Yakubovich SD: Broadband near-IR double quantum-well heterostructure superluminescent diodes. Quantum Electron. 2008, 38: 744–746. COI number [1:CAS:528:DC%2BD1cXhsV2jsLzJ]; Bibcode number [2008QuEle..38..744A] COI number [1:CAS:528:DC%2BD1cXhsV2jsLzJ]; Bibcode number [2008QuEle..38..744A] 10.1070/QE2008v038n08ABEH013772View Article
- Ong T, Yin M, Yu Z, Chan Y, Lam Y: High performance quantum well intermixed superluminescent diodes. Meas. Sci. Technol. 2004, 15: 1591–1595. COI number [1:CAS:528:DC%2BD2cXmvFals78%3D]; Bibcode number [2004MeScT..15.1591O] COI number [1:CAS:528:DC%2BD2cXmvFals78%3D]; Bibcode number [2004MeScT..15.1591O] 10.1088/0957-0233/15/8/028View Article
- Shu-Shen L, Jian-Bai X: Effective-mass theory for coupled quantum dots grown on (11 N)-oriented substrates. Chin. Phys. 2007, 16: 1–5. Bibcode number [2007ChPhy..16....1L] Bibcode number [2007ChPhy..16....1L] 10.1088/1009-1963/16/1/001View Article
- Liang BL, Wang ZM, Sablon KA, Mazur YI, Salamo GJ: Influence of GaAs substrate orientation on InAs quantum dots: surface morphology, critical thickness, and optical properties. Nanoscale Res. Lett. 2007, 2: 609–613. COI number [1:CAS:528:DC%2BD1cXlslejsL4%3D]; Bibcode number [2007NRL.....2..609L] COI number [1:CAS:528:DC%2BD1cXlslejsL4%3D]; Bibcode number [2007NRL.....2..609L] 10.1007/s11671-007-9103-3View Article
- Wang L, Li M, Xiong M, Zhao L: Effect of interfacial bonds on the morphology of InAs QDs grown on GaAs (311) B and (100) substrates. Nanoscale Res. Lett. 2009,4(7):689–693. COI number [1:CAS:528:DC%2BD1MXnt1Skt7g%3D]; Bibcode number [2009NRL.....4..689W] COI number [1:CAS:528:DC%2BD1MXnt1Skt7g%3D]; Bibcode number [2009NRL.....4..689W] 10.1007/s11671-009-9304-zView Article
- Henini M: Properties and applications of quantum dot heterostructures grown by molecular beam epitaxy. Nanoscale Res. Lett. 2006, 1: 32–45. Bibcode number [2006NRL.....1...32H] Bibcode number [2006NRL.....1...32H] 10.1007/s11671-006-9017-5View Article
- Henini M: High index surfaces grow novel devices. III-Vs Rev. 1998, 11: 48–52. 10.1016/S0961-1290(98)80019-7
- Yazdanpanah VR, Wang ZM, Salamo GJ: Highly anisotropic morphologies of GaAs(331) surfaces. Appl. Phys. Lett. 2003, 82: 1766. COI number [1:CAS:528:DC%2BD3sXhvV2ksrg%3D]; Bibcode number [2003ApPhL..82.1766Y] COI number [1:CAS:528:DC%2BD3sXhvV2ksrg%3D]; Bibcode number [2003ApPhL..82.1766Y] 10.1063/1.1561571View Article
- Sanguinetti S, Gurioli M, Henini M: Built-in electric fields in InAs quantum dots grown on (N11) GaAs substrates. Microelectron. J. 2002, 33: 583–588. COI number [1:CAS:528:DC%2BD38XksFKnsbk%3D] COI number [1:CAS:528:DC%2BD38XksFKnsbk%3D] 10.1016/S0026-2692(02)00023-XView Article
- Wen H, Wang ZM, Salamo GJ: Atom-resolved scanning tunneling microscopy of (In,Ga)As quantum wires on GaAs(311)A. Appl. Phys. Lett. 2004, 84: 1756. COI number [1:CAS:528:DC%2BD2cXhvFCjt7s%3D]; Bibcode number [2004ApPhL..84.1756W] COI number [1:CAS:528:DC%2BD2cXhvFCjt7s%3D]; Bibcode number [2004ApPhL..84.1756W] 10.1063/1.1664018View Article
- Niki N, Morita K, Kitada T, Isu T: Optical anisotropy of strained quantum wells on high index substrates. Phys. Status Solid. (c) 2008, 5: 2756–2759. COI number [1:CAS:528:DC%2BD1cXpsVyitbk%3D]; Bibcode number [2008PSSCR...5.2756N] COI number [1:CAS:528:DC%2BD1cXpsVyitbk%3D]; Bibcode number [2008PSSCR...5.2756N] 10.1002/pssc.200779225View Article
- Wang ZM, Seydmohamadi S, Lee JH, Salamo GJ: Surface ordering of (In,Ga)As quantum dots controlled by GaAs substrate indexes. Appl. Phys. Lett. 2004, 85: 5031. COI number [1:CAS:528:DC%2BD2cXhtValtbjJ]; Bibcode number [2004ApPhL..85.5031W] COI number [1:CAS:528:DC%2BD2cXhtValtbjJ]; Bibcode number [2004ApPhL..85.5031W] 10.1063/1.1823590View Article
- Xie YZ, Kunets VP, Wang ZM, Dorogan VG, Mazur YI, Wu J, Salamo GJ: Multiple stacking of InGaAs/GaAs (731). Nano Micro Lett. 2009, 1: 1–3. COI number [1:CAS:528:DC%2BC3cXjvFemtrk%3D] COI number [1:CAS:528:DC%2BC3cXjvFemtrk%3D]View Article
- Polimeni A, Patanè A, Henini M, Eaves L, Main PC, Sanguinetti S, Guzzi M: Influence of high-index GaAs substrates on the growth of highly strained (InGa)As/GaAs heterostructures. J. Cryst. Growth 1999, 201–202: 276–279. 10.1016/S0022-0248(98)01339-6View Article
- Henini M, Sanguinetti S, Brusaferri L, Grilli E, Guzzi M, Upward MD, Moriarty P, Beton PH: Structural and optical characterization of self-assembled InAs-GaAs quantum dots grown on high index surfaces. Microelectron. J. 1997, 28: 933–938. 10.1016/S0026-2692(96)00132-2View Article
- González-Borrero PP, Lubyshev DI, Petitprez E, La Scala N, Marega E, Basmaji P: Optical properties of natural InxGa1-xAs quantum dots grown on high-index GaAs substrates. Braz. J. Phys. 1997, 27: 65–75.
- Nötzel R, Eissler D, Hohenstein M, Ploog K: Periodic mesoscopic step arrays by step bunching on high-index GaAs surfaces. J. Appl. Phys. 1993, 74: 431. Bibcode number [1993JAP....74..431N] Bibcode number [1993JAP....74..431N] 10.1063/1.354128View Article
- Li S, Xia J: Effective-mass theory for GaAs/Ga1-xAlxAs quantum wires and corrugated superlattices grown on (311)-oriented substrates. Phys. Rev. B 1994, 50: 8602–8608. COI number [1:CAS:528:DyaK2cXmtlylt7k%3D]; Bibcode number [1994PhRvB..50.8602L] COI number [1:CAS:528:DyaK2cXmtlylt7k%3D]; Bibcode number [1994PhRvB..50.8602L] 10.1103/PhysRevB.50.8602View Article