Enhanced Performance Photodetector
This research involves the development of high performing sensors that make use of several types of electromagnetic resonance (ER) modes to “channel” and “localize” light. This work has allowed dramatic enhancements in Si, InGaAs and other semiconductor photodetectors. One type of Si photodetector studied in particular are metal-semiconductor-metal photodetectors (MSM-PD). Read More >>
High Efficiency Solar Cells
Novel multiple quantum well (MQW) based solar cells can improve photovoltaic conversion efficiency. The maximum energy conversion efficiency of a conventional solar cell is limited to ~33% because of a mismatch between the broad solar spectrum and the single band gap (Egap) in a conventional solar cell. Solar photons with energy EEgap generate electron-hole pairs, which lose all energy in excess of Egap. Radiative and non-radiative carrier recombination contributes to further reduction in efficiency.
Theoretically, much higher conversion efficiency than that of conventional solar cells (~50% for two band gap cell) can be achieved using multiple band-gap solar cells that accommodate a greater portion of the solar spectrum. Multiple band-gap solar cells can be made from either a multi-junction cell or an MQW cell. The latter behaves as a two-band solar cell, in which wells act as narrow band cells and barriers act as a wide band cells. For several materials studied, the efficiency of MQW solar cells exceeds that of comparable single-band-gap cells made of the well or barrier material alone. The logical extension of this design is to combine several MQW structures with different band gaps in order to expand coverage of the solar spectrum.
We have developed a novel approach to improve solar cell efficiency using specially designed III-V MQW-based structures with a sequential resonant tunneling geometry. Read More >>