Substitutional, interstitial, and neutral zinc incorporation into InP grown by atmospheric pressure metalorganic vapor phase epitaxy

Abstract

Substitutional zinc incorporates linearly into device quality InP at low Zn source flow rate grown by atmospheric pressure metalorganic vapor phase epitaxy (AP-MOVPE) at 625 °C, and saturates around 4×1018 cm-3 at high Zn source flow rate. Increase in the Zn source flow rate beyond saturation significantly enhances interstitial incorporation. The excess interstitial diffuses into the undoped region via an interstitial-substitutional diffusion mechanism and reveals itself as an enhanced diffusion. Previously we have proposed a surface adsorption-desorption-trapping model for substitutional Zn incorporation during AP-MOVPE, where the saturation level is determined by the surface incorporation sites for substitutional Zn. This model is applied to interstitial Zn incorporation at Zn source flow rate above the saturation level for substitutional Zn to explain the enhanced Zn diffusion. The analysis is further extended to the incorporation of neutral Zn in the presence of excess phosphorus vacancies, therefore, this model can be used for simultaneous incorporation of Zn of all three types during epitaxy as long as the incorporation processes are independent. © 1990 American Institute of Physics.