Carrier Density Modulation in PbSe Quantum Dot Films via In-Solution Ligand Exchange

In-solution ligand exchange of PbSe QDs is used to examine the effect of capping ligand on the carrier density of PbSe QD films. Results show that carrier density can be modulated by a factor of 5 by choice of ligand without any additional post deposition treatments. Proper fabrication and measurement conditions for calculating carrier densities from C-V measurements using a sandwich structure on P-doped Si/SiO2/Al2O3/QD/Au structure capacitance devices are outlined. Combining carrier density results with field-effect-transistor measurements, promising ligands which display lower carrier densities without having a significant drop off in carrier mobility are identified as candidates for photodetection purposes.

A Novel Room Temperature Infrared Detector Using Micro-Compensated Amorphous Silicon

ABSTRACTDetection at room temperature of near and medium infrared radiation has been achieved by using micro-doped or micro-compensated amorphous silicon films as intermediate absorber layer in a p-n junction. Extremely low dopant concentrations in the gas mixture have been utilized to achieve micro-doping and micro-compensation. Device operation is based on transitions, induced by the infrared radiation, between extended states in the valence band and defects in the forbidden gap. The absorption process changes electron defect occupancy, giving rise to change in electric field distribution. This effect can be observed as variation of differential capacitance of the structure. Capacitance measurements, performed on two different devices with micro-doped and micro-compensated absorber layer respectively, showed sensitivity to radiation from 900 nm up to 4·5 jim.