Analysis of extended defects in InGaAIP grown by metal-organic chemical vapour deposition using tertiary- butyl phosphine

Abstract

In this thesis, evidence of the existence of a band of trap states with energy in close proximity is presented. A minimum threshold filling pulse width is found to exist for carrier capture and subsequent emission to occur. Conventional DLTS theory does not take into account the dependence of DLTS signal on filling pulse width, tp. Another contribution of the work in this thesis lies in the study of the behaviour of extended defects in response to tp. When the capture process dominates, activation energy decreases with tp. Further increase in tp hinders carrier capture during the filling pulse due to charge screening around the dislocation core, causing an increase in activation energy. A mathematical model is developed to relate the trap activation energy, to filling pulse width. The ratio of emission rate to capture rate declined from 2.5 to 1 when system attains equilibrium.