Tunnel excess current in nondegenerate barrier (p-n and m-s) silicon-containing III–V structures

Abstract

Data are scaled from a study of the forward current in three types of barrier structure: p-n homostructures p-n-GaP/n-Si, p-n-GaAs-n-GaP/n-Si, and p-n-GaAs-n-GaAs/n-Si; heterostructures n-GaP/p-Si, p-GaP/n-Si, n-GaAsP/p-Si, and n-GaAs/p-Si; and Au-n-GaP/ n-Si surface-barrier structures. Epitaxial layers of GaP and GaAs were created on Si-substrates by gaseous phase epitaxy in a chloride system. Temperature measurements show that the forward current has a tunnel character, although the width of the space charge region greatly exceeds the tunneling length. A model is proposed for nonuniform tunneling along dislocations that intersect the space charge region. This type of tunneling is taken into account by introducing a phenomenological “dilution” factor for the barrier. The model makes it possible to calculate the dislocation density in device structures from the current-voltage characteristic.