University of Delaware - College of Engineering



Dilute Nitride Technology for Infrared Detectors

James Kolodzey

Dilute nitride semiconductors have been proposed as a good choice for mid- and long-waver infrared detectors, because theoretical analysis has shown that a small amount of nitrogen in antimonide semiconductors is capable of drastically lowering the bandgap and enhancing the recombination parameters, carrier confinement, transport properties and temperature characteristics of the detector materials and devices. Thus far, the potential of dilute nitride materials has not been realized because of the challenges and difficulties of incorporation of even minute quantities of nitrogen in III-V compound semiconductors. These difficulties include achieving the optimum growth conditions, the high lattice mismatch for the material responsive to VLWIR and the high background doping.

With another faculty member (Prof. Goossen), we have been working with a small business, Epitaxial Technologies, to develop dilute nitride strained layer superlattices in the design of detectors. We used semiconductor modeling software, the FemB k•p computer simulation software package from Quantum Semiconductor Algorithms, Inc (QSA), to simulate the properties of dilute nitride structures. This software uses the k•p technique for the calculation of electronic eigenstates in semiconductor quantum structures. The k•p technique is an approximation method that calculates energy versus wavevector dispersion, and wave functions in vicinity of band critical points in k space such as the  point.

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