A HIGH QUANTUM EFFICIENCY INSITU DOPED MIDWAVELENGTH INFRARED P-ON-N HOMOJUNCTION SUPERLATTICE DETECTOR GROWN BY PHOTOASSISTED MOLECULAR-BEAM EPITAXY

HgTe/CdTe superlattices in infrared (IR) detector structures have been theoretically shown to allow for better control over cutoff wavelength, minimize diffusion currents, and greatly reduce band-to-band tunneling currents as compared with the corresponding HgCdTe alloy. However, the few HgTe/CdTe superlattice detectors that have been fabricated exhibit little or no quantum efficiency. In this paper, we report the first high quantum efficiency mid-wavelength infrared (MWIR) detectors based on HgTe/CdTe superlattices. This result is significant because it represents the first experimental verification that IR detectors with useful characteristics can in fact be fabricated from HgTe/CdTe superlattices. The MWIR detectors were fabricated from an in situ doped p-on-n MWIR homojunction superlattice epilayer grown by photoassisted molecular-beam epitaxy (PAMBE). This growth technique produces low defect growth of superlattice material, as is described in this paper. Our development of an extrinsic doping technology using indium and arsenic as the n-type and p-type dopants, respectively, led to the successful doping of the superlattice and is also discussed.