<title>Mobility spectrum techniques for characterizing multilayer semiconductor structures</title>

Abstract

While differential Hall measurements are a standard approach to determination of junction depth in multi-layer semiconductors, significantly more information can be obtained from magnetic field dependent differential Hall measurements. When such measurements are treated using Quantitative Mobility Spectrum Analysis (QMSA), detailed depth resolved profiling of both carrier concentrations and mobilities can be achieved, giving important data directly related to potential device performance. The doping profile is obtained by performing a series of etch-back experiments with magnetic field dependent Hall measurements performed between the etching steps. This technique is illustrated on a number of vacancy and gold doped Hg<SUB>1-x</SUB>Cd<SUB>x</SUB>Te p-type epilayers, which have been partly or wholly converted to n-type by a reactive ion etching (RIE) process. The QMSA analysis reveals that there are several electron species present in the layers as well as the original p-type carrier. The electron species have been identified as low mobility surface electrons, and high and low mobility electrons located at various depths through the epilayer. It also indicates that the p-to-n conversion depths range from less than 0.5micrometers for vacancy doped Hg<SUB>0.7</SUB>Cd<SUB>0.3</SUB>Te material, to more than 17micrometers for Au-doped Hg<SUB>0.8</SUB>Cd<SUB>0.2</SUB>Te for the same type conversion conditions.