TIME-RESOLVED PHOTOREFLECTANCE OF GAAS AND INALAS

We have measured the Schottky barrier heights of pinned and unpinned s emiconductor systems by photoreflectance in terms of the Franz-Keldysh oscillations in frequency domain and the characteristic times in time domain. The structure of the pinned system is delta-doped GaAs homoju nctions and that of the unpinned system is InAlAs surface-intrinsic-n( +) structure. In time domain, the rise and fall times were determined by digital oscilloscope. From the characteristic times obtained, we ca n determine the potential barrier heights for both structures. The bar rier heights determined by the characteristic times for GaAs pinning s ystem and InAlAs unpinning system are, respectively, 0.68 eV and 0.63 eV, and are in good agreement with those obtained from Franz-Keldysh o scillations.