Visible-Infrared photodetector based on (delta)-Si doped InGaAs quantum well

摘要

Full text. The semiconductors thin films with doping level near Anderson transition have high photosensitivity in the photoconductivity regime. The maximum sensitivity these photodetectors have when under illumination the system transform from semi-insulating to semi-metal. The ratio between deep and shallow levels concentration for this case should be near unity at total impurity concentration near 10(sup 15) cm(sup -3), that difficult to control at the bulk doping. The frequency response in this devices are limited by absorption thickness ((approx)500-300 nm). In present work report the results of visible-infrared photodetector (PD) preparation by using molecular beam epitaxy. For development of frequency response and wavelength range increase to infrared area we use (delta)-doped In (sub 0.2) Ga (sub 0.8) As quantum well. The doping level in (delta)-Si layer on the middle of QW was 2 x 10(sup 12) cm(sup -3), that was enough for shift of deep levels-shallow levels concentration ratio to Anderson transition in the are near QW. At the illumination all photoexcited carriers was collected by QW. The deepness of photo sensible space area is limited by new nanometers near the QW, that increase the frequency properties of PD. Photocurrent spectra show high sensibility (Delta)R/R=155 at cut-off frequency up 1.25 eV. This explain strong optical absorption by QW in the infrared area. The future work will focalized on introducing (delta)-doped In Ga As superlattice for linearization of PD spectrum characteristics. (author)