ZnTe is a promising material for pure green LED. Phosphorus (P) is considered to be a suitable species for p-type dopant in ZnTe, since the pure green LED is obtainable by a thermal diffusion of Al into P-doped p-type ZnTe. In our previous study, we have grown P-doped ZnTe layers by MOVPE using tris-dimethylaminophosphorus (TDMAP). Although the layer with a high carrier concentration of 1.3×10¹⁸ cm^-3 can be obtained, it shows only donor-accepter pair emission (DAP) in the low temperature photoluminescence (PL) spectrum. In order to improve the P-doped ZnTe layer, we have investigated the post-annealing treatment (PAT), which is expected as one of the approaches for overcoming this problem.

The samples for PAT were as-grown P-doped ZnTe layers prepared by vertical MOVPE at atmospheric pressure on Ga-doped (100) ZnTe substrates using TDMAP as a dopant source. They were annealed in N₂ flow at a low temperature of 420 ºC for 2 h. In order to investigate the effect of PAT upon the P-doped ZnTe layers, the PL spectra of the layers were compared before and after PAT.

The PL properties of the layers are drastically influenced by PAT. In each spectrum of the annealed layers, DAP vanishes and instead free-to-bound transition emission and broadened acceptor-related excitonic emission (I_a) appear. These changes indicate the reduction of the compensation and an activation of the P atoms, which may be a result of the decrease in the number of the defect related donor and/or the displacement of P atom into regular lattice site of Te by PAT. The broadened I_a shift towards lower energy side with increasing dopant transport rate, indicating the carrier concentration is enhanced by PAT.

This study was supported by Industrial Technology Research Grant Program in 2005 from NEDO of Japan.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/8120 must be provided.

1. SIMS study of Al thermal diffusion in ZnTe