SOL ID STATE " SC IENCE, Analysis of N-Type GaAs with Electron-Beam-Excited

The study of spontaneous emission for n-type GaAs has shown that the spectral shape and peak position may be utilized to determine the free elec-tron concentration within ___15 % near concentrations of 5 x 1017 cm-8 and • at 5 x 10 ls cm-3. Excitation of the sample with a 1 ~ diameter electron beam gives such sensitivity with a 3-6 ~ spatial resolution. This sensitivity and spatial resolution are sufficient for investigating sample inhomogeneities that are related to the spatial variations in the quantum efficiency. Several investigations (1,2) of radiative recom-bination in heavily doped GaAs have shown that the photoluminescent peak shifts to higher energy as the donor concentration is increased above 5 x 1017 cm-~. Cusano (3) has reported data demonstrating the de-pendence of the cathodoluminescent (electron-beam excitation) peak energy and the spectral half-width o