Optical and electrical properties of undoped and doped Ge nanocrystals

Table 3 Size of Ge nanocrystals

Embedded matrix^a	PL peak energy (eV)	d_NC [confinement model] (nm)^b	d_NC (TEM) (nm)^b
HfO₂ ('RF')	1.67	7.1	7.8
Al₂O₃ ('RA')	1.75	6.6	7.1
SiO₂ ('RS-2')	2.12	5.9	5.3

^aGe nanocrystals embedded in different oxide matrices and ^bd_NC, nanocrystal diameter; PL, photoluminescence; TEM, transmission electron microscopy; 'RF', 'RA', and 'RS-2', sample structures defined in Table 1.