Post-growth spectral tuning of InGaAs/GaAs quantum dot infrared photodetectors [article]

Ian Robert McKerracher, University, The Australian National, University, The Australian National
Infrared photodetectors are essential in many industries and modern applications require devices with enhanced capabilities. High-performance detectors can be used for spectroscopy in medicine and environmental monitoring. Imaging scenarios include the identification of military targets and predicting equipment failure. These thermal imaging systems benefit from multicolour photodetectors. For example, some heat-seeking missiles incorporate two-colour HgCdTe arrays to discern target aircraft
more » ... target aircraft from decoy flares. Hyperspectral imaging describes the fusion of imaging and spectroscopy. These systems exhibit high spatial and spectral resolution, generally by dispersing different wavelengths onto a focal-plane array. Agricultural surveys, extraterrestrial exploration and medical procedures can all benefit from this powerful technique. High-end detectors in the mid-wavelength and long-wavelength infrared are usually made from HgCdTe alloys. These narrow-bandgap semiconductors exhibit favourable optoelectronic properties, however fabrication challenges lead to extravagant costs. In comparison, mature fabrication processes are available for III-V materials. Interband photodetectors made from these compounds are only sensitive at shorter infrared wavelengths. In recent years, intersubband devices have been developed for longer wavelengths and quantum well infrared photodetectors are now commercially available. Focal-plane arrays made from these structures are cheaper and the yield is better than with the HgCdTe technology. Quantum dot infrared photodetectors can also be fabricated from III-V materials. These architectures are inherently sensitive to normal-incidence radiation and have long carrier lifetimes, so they are expected to out-perform their quantum well counterparts. The devices studied here may be applicable to meteorology, atmospheric monitoring, molecular biology and medicine. High-quality quantum dots are normally grown by self-assembly and this restricts their size and composition. Hence, directly fabricating [...]
doi:10.25911/5d666b615239f fatcat:jh3wogs6vbaljolbchham7zxky