Chromium profiles in semi-insulating GaAs after annealing with a Si3N4 encapsulant

Abstract

Quantitative Cr profiles have been determined on semi-insulating GaAs by secondary-ion mass spectrometry (CAMECA IMS 300). It is shown that after thermal annealing (900 °C, 20 min) under Si3N4, Cr diffuses towards the GaAs surface, leaving a Cr concentration depletion zone underneath. This zone becomes conductive with a carrier concentration of n∼2×1016 cm−3. Some consequences of these findings are considered.