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The optical and electrical properties of infrared photodiodes diodes based on InAs/(GaIn)Sb superlattices grown by molecular beam epitaxy were investigated. The diodes, with a cut-off wavelength around 8 µm show a current responsivity of 2 A/W. By proper adjustment of the p-doping level above the n-background concentration the depletion width exceeds a critical size of about 60 nm, leading to the suppression of band-to-band tunneling currents. Above that critical width the dynamic impedance R0A at 77 K reaches values above 1 kV cm2 leading to a Johnson-noise-limited detectivity in excess of 1X10(12) cm/Hz/W

Trap centers with an energy level positioned 1/3 of the band gap below the effective conduction band edge are observed in the electroluminescence spectra of InAs/(Galn)Sb superlattice photodiodes with a cutoff wavelength of 11 µm. The trap centers are recognized by simulating the low-temperature current-voltage characteristics of the diodes. Excellent quantitative agreement on both, the l- V characteristic and the differential resistance between the experimental data and the theoretical prediction is achieved. The quantitative simulation of the I- V characteristics shows, that the 77 K performance of InAs/(Galn)Sb photodiodes is dominated by generation-recombination processes even at long wavelengths. Above 50 K, tunneling currents are not of importance

There is a high demand for compact low-cost ozone sensors. It has been shown recently that In2O3 nanolayers can act as ozone sensitive films activated at room temperature by ultraviolet light. In the present work, the authors integrate ultrathin layers of In2O3 nanoparticles and a GaInN∕GaN based blue light emitting diode (LED) on a single sensor chip. The integrated sensor was found to be sensitive to O3 concentrations as low as ∼40ppb. These results demonstrate that by integrating GaInN∕GaN based blue LEDs and metal oxide sensing layers back to back on a single chip, compact and robust gas sensors can be realized.

Nonthermal rollover (or efficiency droop) of the electroluminescence (EL) efficiency has been investigated for near-UV-emitting (AlGaIn)N single-well light-emitting diodes (LED) with varying GaInN well widths grown on substrates with different dislocation densities (DDs). For each DD the well width of the mesa-LEDs has been optimized for maximum EL efficiency at high operating currents. LEDs on freestanding GaN (DD 4 x 10(exp 7) cm-2) with an 18 nm thick GaInN wide-well active region show the highest efficiency, and the output power-versus-current characteristic remains linear up to the highest pulsed current density of 750 A/cm2. In contrast, LEDs on sapphire grown with conventional low-temperature nucleation (DD 10(exp 9) cm-2) exhibit the optimum well width a 3 nm and show significant nonthermal rollover