SI SIGE VALENCE-BAND OFFSET DETERMINATION USING PHOTOLUMINESCENCE ANDDLTS IN SIGE QUANTUM-WELL MOS CAPACITORS/

Optical and electrical characterization is carried out on MOS capacito r structures including buried strained Si1-xGex quantum-wells to deter mine the channel and hetero-interface parameters. Well resolved SiGe b and-gap edge Photoluminescence (PL) is observed for all the samples. T he energy locations are in agreement with the announced Ge contents an d quantum-well thickness. The presence of dislocations is not detected , indicating a good Si/SiGe interface structural quality. The results show that the hole concentration in the quantum-well is a function of the pulse duration (t(p)) of the excitation signal used for the DLTS s pectroscopy. Using the DLTS, the valence-band offset (Delta E-v) is de termined for various Ge contents up to 35%. This work points out that the coupling of the optical (PL) and electrical (C-V and DLTS) charact erization provides a consistent tool for the analysis of Si/SiGe heter ostructure based devices. (C) 1998 Elsevier Science B.V. All rights re served.