Strategies for Direct Monolithic Integration of AlxGa(1-x)As/InxGa(1-x) As LEDS and Lasers On Ge/GeSi/Si Substrates Via Relaxed Graded GexSi(1-x) Buffer Layers.

摘要

Al(x)Ga(1-x)As/GaAs quantum well lasers have been demonstrated via organometallic chemical vapor deposition (OMCVD) on relaxed graded Ge/Ge(x)Si(1- x) virtual substrates on Si. Despite Un-optimized laser structures with high series resistance and large threshold current densities, surface threading dislocation densities as low as 2 x 10(exp 6)/sq cm enabled cw room-temperature lasing at a wavelength of 858 nm. The laser structures are oxide-stripe gain- guided devices with differential quantum efficiencies of 0.16 and threshold current densities of 1550A/sq cm. Identical devices grown on commercial GaAs substrates showed differential quantum efficiencies of 0.14 and threshold current densities of 1700A/sq cm. This comparative data agrees with our previous measurements of near-bulk minority carrier lifetimes in GaAs grown on Ge/GeSi/Si substrates. A number of GaAs/Ge/Si integration issues including thermal expansion mismatch and Ge autodoping behavior in GaAs were overcome.