Direct Observation of Minority Carrier Leakage in Operating Laser Diodes by Kelvin Probe Force Microscopy

摘要

A new approach to investigating the leakage of nonequilibrium holes and electrons from the active region of a semiconductor laser diode is proposed. According to this, the scanning Kelvin probe force microscopy is used to measure averaged local changes in the contact potential difference on the surface of laser mirrors of a device operating at a pulsed bias voltage. It is shown that the measured signal level is determined by the degree of charge exchange between the slow surface states and nonequilibrium minority carriers, the concentration of which is directly related to the leakage current.