Molecular beam epitaxy of quantum dots for high-speed photodetectors.

摘要

Recent progress in the fabrication of III-V self-assembled semiconductor quantum dots (QDs) and unique physical properties of QDs (three-dimensional confinement of carriers, discrete density of states, the ability to grow defect-free layers past the critical thickness) has stimulated the interest in the implementation of QD material in the photodetector devices. The systematic study of In 0.5Ga0.5As QDs grown by two different techniques: regular molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE) is presented in this work. Photoluminescence (PL), atomic force microscopy (AFM) and intensity-dependent luminescence (IDPL) study were used to evaluate the formation and evolution of QDs. A resonant-cavity (RC) p-i-n photodiode with two QD absorbing regions consisting of a stack of QD layers with a peak quantum efficiency of 65% at 1.06 mum is demonstrated. Also described the separate absorption, charge and multiplication (SACM) QD avalanche photodiode (APD) operating at 1.06 mum with 57% quantum efficiency and record high gain-bandwidth product of 220 GHz. Evaluation of the use of QDs for 1.3 mum detection is presented in this work.