Effect of surface pre-treatments on carrier depletion at growth-interrupted p-type InP interfaces for laser structures grown by GSMBE

The authors report on the effects of two different surface cleaning procedures aimed at improving the quality of growth-interrupted p-type InP interfaces: (i) an oxide encapsulation technique and (ii) an in-situ ECR (electron cyclotron resonance) hydrogen plasma treatment. The surface properties are investigated using XPS and RHEED (reflection high energy electron diffraction), and interfaces are characterized using C-V and SIMS profiling techniques. The effect of residual surface impurities and surface stoichiometry on the origin of the carrier depletion layer is discussed. The ex situ oxide encapsulation approach can be easily used and gives significant enhancement. However, its quality is limited by residual interfacial impurities. The in situ ECR hydrogen plasma/P/sub 2/ technique can, under certain conditions, provide ideal interfaces free from carrier depletion when the treatment is performed on growth-suspended interfaces. It appears to be the most promising approach, but further work is needed to confirm its potential.<>