Effect of V/III ratio on the optical properties of MOCVD grown undoped GaAs layers

A detailed analysis of low temperature photoluminescence (PL) spectro- scopy on undoped high quality GaAs is presented. For undoped GaAs epitaxial layers grown by low pressure metal organic chemical vapor deposition under different V/III ratios, an optimum ratio corresponding to a minimum number of shallow impurities was clearly identified. The V/III ratio has strong effect on the optical properties of undoped GaAs epitaxial layers, When the V/III ratio was varied from 45 to 87, the electron concentration, n, of undoped GaAs increased with increasing V/III ratio. Below the V/III ratio of 45 in our case, the sample exhibited a p-type behavior, which has been identified by photoluminescence as well as depth profiling by Electra-chemical Capacitance Voltage (ECV) profiler