Effect of surface treatment on properties of ZnTe LED fabricated by Al thermal diffusion

Three kinds of surface treatments of ZnTe have been investigated for the fabrication of the light emitting diode (LED) by Al thermal diffusion. In case that a wet cleaning process was used, a poly‐crystalline layer remains on the surface of ZnTe whereas a clean surface was obtained by using in situ thermal or H radical cleaning processes. However, a series resistance of the LED fabricated on a clean surface is much higher than those fabricated using the wet cleaning process, indicating that a clean interface leads to a formation of a heavily Al doped layer with high compensation by the Al diffusion. Based on these results, we have attempted to control an interface by inserting an oxide layer intentionally on a clean surface of ZnTe. As a consequence, we have found that an Al concentration in the diffused layer can be controlled by changing the thickness of the oxidation layer, resulting in obtaining a LED with better performance. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)