High–speed Low–noise Short–wavelength Infrared Type–II Superlattice Heterojunction Phototransistor

Heterojunction phototransistors (HPTs) are an alternative technology that can demonstrate both high speed and internal gain. Functionally, a HPT is a pin photodiode integrated with a bipolar transistor to form an integrated amplifier. Unlike avalanche photodiodes (APDs), HPTs can provide large photocurrent gain without requiring high bias voltages or the excess avalanche noise characteristic of avalanche photodiode operation. This makes them ideal for high speed infrared imaging applications. Here we propose to make heterojunction phototransistor based on type-II superlattices for SWIR and MWIR spectral regions. This device is unique because all parts of it are going to be made of an artificial III-V based meta-semiconductor (T2SLs). This new superlattice design is expected to show high gain×bandwidth (~ 1 GHz) while maintaining high specific detectivity (D* ~ 1013 Jones) as the state-of-the-art photodetector technologies. This mater can be achieved by improving material growth quality, selecting a proper superlattice designs, and improving the device processing techniques. This new design also possesses the same inherent advantages that Type-II superlattices have over the competing technologies like MCT and QWIP family such as a large effective mass which results in a decrease in the dark current and the flexibility of band engineering which can be exploited to suppress Auger recombination as well as the robustness of the III-V compounds compared to MCT materials. The Center for Quantum Devices (CQD) is a world renowned research group founded by the Center’s director, Professor Manijeh Razeghi, in 1992. Under Professor Razeghi’s leadership, the CQD has assembled a strong team of graduate and undergraduate students, research scientists, and professors—all with diverse backgrounds and expertise covering a wide range of disciplines. We are one of the premier experts in the area of Type-II superlattices and hold many of the word records for using this material system to realize focal plane array cameras. We have also recently demonstrated initial Heterojunction phototransistors (HPTs) based on Type-II superlattices. We are ideally suited to complete the proposed work developing these new detectors for imaging applications. As a single investigator team we have all of the necessary capabilities in house and can perform the proposed work rapidly and for minimal costs.