Dislocation-induced deep electronic states in InP: Photocapacitance measurements

Abstract

Photocapacitance and excitation photocapacitance methods were applied to reveal the dislocation-induced deep levels in coalescent epitaxial lateral overgrowth layers of InP. Point-contact Schottky barrier junctions with small junction areas were formed on dislocated and dislocation-free regions by using wedge wire-bonding of Au, and photocapacitance measurements were then carried out at $30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. In the dislocation-free layers, the dominant deep level was located at $1.30\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ below the conduction band, whereas in the dislocated area, dominant deep levels were detected at $0.86\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ $(\ensuremath{\lambda}=1.44\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m})$ and $1.05\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ $(\ensuremath{\lambda}=1.18\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m})$ below the conduction band. A neutralized state was also detected at $0.66\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ above the valence band. From the detailed excitation photocapacitance results, it is shown that the defect configuration coordinate diagram of the dislocation-induced deep levels was considered with large Frank-Condon shifts $({d}_{\mathrm{FC}})$ of $0.28\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. This means that the atomic configurations around the deep levels are highly relaxed, as expected from the structures of the dislocation cores.