Capacitance Spectroscopy of n-i-n and p-i-p GaAs Sandwich Structures with Nanoscale As Clusters in the i-Layers

摘要

Accumulation of electrons and holes in GaAs layers, that contained As clusters and were sandwiched between n- and p-type buffer GaAs layers, was revealed by capacitance-voltage measurements. As a result of majority-carrier accumulation, expansive depletion regions are formed in the adjoining buffer layers. Simulation of the capacitance-voltage characteristics, based on a numerical solution of the Poisson equation, shows that the accumulated charge density is ～1 x 10~(12) cm~(-2), which is comparable with the concentration of As nanoclusters determined by transmission electron microscopy. The levels where the electrons or holes are accumulated lie close but above the GaAs midgap. A strong difference in the emission rates of the accumulated electrons and holes has been revealed.