PHOTOREFLECTANCE AND C-V MEASUREMENT INVESTIGATIONS OF DRY-ETCHED GATE RECESSES FOR GAINP INGAAS/GAAS PSEUDOMORPHIC HIGH-ELECTRON-MOBILITY TRANSISTORS (HEMTS) USING BCL3/AR PLASMA/

Photoreflectance (PR) spectroscopy and capacitance-voltage (C-V) measu rements are used to characterize the surface damage caused by BCl3/Ar plasma in barrier layer of GaInP/GaInAs/GaAs pseudomorphic high electr on mobility transistors (PHEMT). When the BCl3/Ar flow ratio is either lower or higher than 6:4: PR spectra indicate plasma causes damage su ch as nonradiative recombination centers; scattering centers and strai n which lead to decreased signal intensity, broadened linewidth, and t he spectral shift, respectively. The plasma-induced surface damage als o results in a positive voltage shift of the C-V curve. By using a BCl 3/Ar mixed gas, the positive voltage shift of the C-V curve is less th an that of samples with pure BCl3. Both PR and C-V measurements are in good agreement. These results show that photoreflectance spectroscopy is a powerful, nondestructive tool for investigating surface damage a nd can be used to improve the performance of PHEMTs.