GaAs wafer mapping by microwave-detected photoconductivity

An improved highly sensitive method of detecting photo conductivity bq micr owave absorption (MDP) is described. The method is applicable to semi-insul ating and low resistivity marterial as well. It is non-destructive and can be applied to epi-layers. MBP topograms art compared with those for photo l uminescence, point contact. and EL2 using the same sample. The MDP-contrast is mainly due to a so far unknown recombination centre determining the car rier lifetime under non-equilibrium. The annealing behaviour of MDP is very similar to that of the point-contact method. In general, MDP has the poten tial to be used as a new tool for material duality inspection with direct e vidence for device properties. (C) 2001 Published by Elsevier Science B.V.