Study on the energy-band structure of Indium-rich InGaN/GaN quantum dot system

Abstract

The ground-state energy levels and energy band structures of the In-rich InGaN/GaN quantum-dot (QD) system were analyzed by performing the capacitance-voltage (C-V), deep-level transient spectroscopy (DLTS), and photoluminescence (PL) measurements. The InGaN QD system was grown by using a metal-organic chemical vapor deposition method. The lateral size, the height, and the density of a disc-shaped InGaN QDs were 47.3 nm, 1.2 nm and 9.0 x log cm(-2), respectively. The ground states of the InGaN QDs were located at 0.44 eV from the top of the barrier, which correspond to the conduction band edge of GaN. The QDs had various levels, except for the ground-state energy. A band-to-band transition energy of 2.92 eV was found by using PL measurements. Moreover, antisite point defects were also founded in GaN buffer layer, and their activation energy and emission cross-section were 0.70 eV and 1.19 x 10(-13) cm(2), respectively.