Growth of large two-dimensional 8-15 um InAs/InGaSb type-II SL photodetector arrays on compliant substrate
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AbstractInAs/InGaSb type-II superlattices have advantages over HgCdTe for photodetectors requiring higher temperature and longer wavelength operation. The type-II QW photodiodes have comparable quantum efficiency, smaller dark current due to a larger effectivemass, much slower Auger recombination rates, and hence much longer carrier lifetimes. Through careful bandgapengineering, we have suppressed the Auger coefficient by a factor of >8 for 4.5 -um type-II lasers at 300 K. In the phase-I program, we havedemonstrated many high-performance photoconductors directly grown on compliant GaAs substrates with a cutoff wavelength from 11 um to 19 um. We have also demonstrated and dramatically improved the quality of 2-inch compliant GaAs substrates. With theimprovement of materials growth and compliant substrates, more than a factor of 1500 of improvement has been achieved in the photoresponse. Further investigations will be performed to optimize the compliant substrates. Additionally, the coherenttunneling at the mesa-surface is the performance pitfall for ungated SLs mesa devices. To solve this issue, we propose to develop the surface passivation technology using sulfide materials to eliminate the side-wall leakage current. Therefore, we will beable to demonstrate large photodiode arrays with a detectivity >5x1012 cmHz 0.5/W at a wavelength of 14, um at 55 K.Critical military needs include missile defense, remote chemical sensing for defense against biological/chemical warfare, and medical.Commercial markets include leak detection, chemical process control, remote chemical sensing for atmospheric pollution and drug monitoring, IR spectroscopy, and medical diagnoses. With the development of high-performance photodectors, this program shouldconsiderably accelerate the commercialization of mid-IR photodetectors to meet the potential needs of the huge defense and commercial market
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