Photoreflectance Spectroscopy Characterization of Ge/Si_0.16Ge_0.84 Multiple Quantum Wells on Ge Virtual Substrate

Table 2

Values of the Varshni- and Bose-Einstein-type fitting parameters, which describe the temperature dependence of the mnH(L) transitions of Ge/SiGe MQW. The direct gaps of bulk Ge also included for comparison.

Samples	Feature	𝐸𝑚𝑛H(L)(0)	𝛼𝑖	𝛽𝑖	𝑎𝐵𝑖	Θ𝐵𝑖	𝑑𝐸𝑚𝑛H(L)/𝑑T
	mnH(L)	(eV)	(×10^−4 eV/K)	(K)	(meV)	(K)	(meV)
Ge/Si0.16Ge0.84 MQW^a	11H	0.958±0.003	7.5±0.8	453±50	61±10	256±30	−0.41
	11L	0.985±0.003	7.5±0.8	485±50	57±10	254±30	−0.38
	22H	1.073±0.003	8.0±0.8	445±50	63±10	250±30	−0.43
Ge/Si0.15Ge0.85 MQW^b	11H	0.968±0.003	7.4±0.8	430±100	59±10	250±30	−0.45
	11L	1.011±0.003	7.2±0.8	400±100	56±10	245±30	−0.44
	22H	1.037±0.003	6.9±0.8	430±100	55±10	250±30	−0.41
(Si4Ge6)5Ge78 MQW^c	11H	0.957±0.003	7.2±1.5	420±150	65±10	290±46	−0.43
	11L	0.984±0.003	6.8±1.5	370±150	60±10	255±46	−0.41
Ge bulk^a	𝐸0	0.892±0.005	6.7±0.8	386±50	57±10	251±30	−0.41
Ge bulk^c	𝐸0	0.885±0.002	6.5±0.7	410±100	66±12	298±35	−0.38

aThis work (photoreflectance).
^bReference [17] (piezoreflectance).
^cReference [29] (piezoreflectance).