Development of narrow gap semiconductor materials and devices for optoelectronic applications

Mid-wave to long-wave infrared (3~12 mum in wavelength) optoelectronic devices have broad applications in gas sensing, molecular spectroscopy, imaging, environmental, industrial monitoring, etc. This work aims to explore new III-V materials and heterostructures to develop light emitting devices and detectors for the infrared spectral region.;Optical properties of dilute nitride GaSbN and InAsN materials were investigated. We observed strong bandgap reduction with increasing nitrogen incorporation. GaSbN with 1.4% of nitrogen showed 300 meV narrower bandgap than GaSb; for InAsN the bandgap energy was reduced by 150 meV with nitrogen incorporation up to 2.25%. The carrier lifetimes within the picoseconds - nanoseconds range were measured for GaSbN and InAsN.;InAs1-xSbx alloys have the smallest bandgap energies within conventional III-V semiconductors. We demonstrated that growing compositionally graded buffers (Ga(Al)InSb on GaSb substrates) allows the fabrication of bulk unstrained and unrelaxed InAs1-xSbx layers with band gap energy as low as 120 meV. Photoluminescence spectra (5 -10 mum) and minority carrier lifetimes (up to 250 ns) were measured.;Light emitting diodes (LEDs) and photodetectors were fabricated using InAs1-xSbx alloys. LEDs with x = 0.2 and x = 0.4 demonstrated output powers of 90 muW at 5 mum and 8 muW at 8 mum respectively, at the temperature of 80 K. Barrier type photodetectors with InAs1-x Sbx (x = 0.4) absorber layer and AlInSb barrier were fabricated. Front side illuminated detectors with 1 mum thick absorber demonstrated an external quantum efficiency of 18 % at 8 mum at 150 K.