Energy level scheme of an InAs/InGaAs/GaAs quantum dots-in-a-well infraredphotodetector structure

摘要

A thorough investigation of the energy level structure in a quantum-dots-in-a-well infrared photodetector has been performed employing different experimental techniques. From photoluminescence (PL) and PL excitation (PLE) spectroscopy an approximate energy level scheme of the conduction and valence band energy structures was deduced. By studying the polarisation dependence of the quantum dot interband transitions, it was revealed that the QDs hold two electron energy levels and two heavy hole levels. An electron energy level separation of 50 meV was deduced from tunneling capacitance measurements. From photocurrent measurements with simultaneous optical pumping a quantum dot - quantum well energy level separation of 150 meV was revealed.