Comparison of Zn-doped GaAs layers prepared by liquid-phase and vapor-phase techniques, including diffusion lengths and photoluminescence

Abstract

p‐type Zn‐doped GaAs layers have been prepared by both liquid‐phase (LPE) and vapor‐phase (VPE) epitaxial growth techniques. Both techniques allow controlled Zn doping between ∼9×10¹⁷ and 3×10¹⁹ cm⁻³. For the LPE technique, the hole concentration (p) is related to the concentration (X_Zn) in the Ga solution by p=5×10²⁰(X_Zn)^1/2. The surfaces of the LPE layers have a characteristic ripple, in contrast to the optically flat surfaces representative of vapor‐grown layers. Minority‐carrier (electron) diffusion lengths in the LPE layers decrease from 10 to 5 μm with increasing hole concentrations between 9×10¹⁷ and 3×10¹⁹ cm⁻³. Diffusion lengths for comparably doped VPE layers are about two times smaller. The room‐temperature photoluminescence characteristics of both types of layers have similar dependences on hole concentration, which can be used as a calibration for nondestructive hole concentration determination. Peak photoluminescence intensities of the two types of layers occur at ∼1×10¹⁹ cm⁻³, and are approximately equal in intensity.