Characterization of Al-doped ZnTe layer using scanning capacitance microscopy and Kelvin probe force microscopy

Abstract

Al-doped ZnTe layer in ZnTe LED fabricated by Al thermal diffusion has been characterized using cross-sectional scanning capacitance microscopy (SCM) and Kelvin probe force microscopy (KFM), and the results were verified by comparing with the result of the electron beam induced current (EBIC) measurements. Both SCM and KFM images showed contrast changes between Al diffusion layer and p-type substrate, indicating the conductivity type conversion in ZnTe. The distance from the surface of ZnTe to the contrast change position was around 1.8 μm, in consistent with the result of EBIC measurement. The surface potential of the Al diffusion layer was found to be almost constant, implying that the diffusion layer is relatively homogenous in depth direction. Thus, SCM and KFM are capable of providing the electrical information on ZnTe LED. © 2007 IOP Publishing Ltd.