Two-Color Infrared Sensor on the PbTe: In p-n Junction.

A lead telluride sensor was fabricated on the base of a p-n PbTe junction created on a PbTe single crystal grown by the Czochralski technique, followed by the diffusion of an indium donor impurity into a crystal. The capacitance-voltage and current-voltage characteristics of the sensor were measured over the temperature range from 80 K to 150 K. A prototype of a high-temperature mid-IR sensor, a PbTe diode, with a cut-off wavelength of 4 µm, operating at temperatures up to 150 K, was demonstrated for the first time. The advantage of the sensor is that its operating temperature is high enough to be reached by a solid-state thermoelectric cooler. The sensor showed a specific detectivity value of 1010 cm Hz1/2/W at a temperature of 150 K and a wavelength of 4.2 µm. The possibility to sense pulses of long-IR radiation by means of the PbTe diode was also demonstrated over the 100-180 K temperature range. For the first time, a two-photon absorption-caused photovoltaic effect was observed in PbTe at a wavelength of 9.5 µm at 150 K.

Cathodoluminescence studies of electron irradiation effects in n-type ZnO.

The lifetime of non-equilibrium carriers in n-type unintentionally doped ZnO increases when the sample is exposed to the electron beam of a scanning electron microscope. This is observed by studying the ZnO cathodoluminescence (CL) spectra at different irradiation time durations and temperatures. We found that the decrease in the CL spectra's peak intensity is related to a thermo-activated energy barrier, determined by the calculated activation energy value of 259 ± 30 meV. This energy value comes close to the defect energy level of the zinc interstitial, which is possibly the nature of the energy barrier responsible for this decrease.

Electrically pumped waveguide lasing from ZnO nanowires.

Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide (ZnO), which has a wide direct bandgap and a large exciton binding energy. ZnO-based random lasing has been demonstrated with both optical and electrical pumping, but random lasers suffer from reduced output powers, unstable emission spectra and beam divergence. Here, we demonstrate electrically pumped Fabry-Perot type waveguide lasing from laser diodes that consist of Sb-doped p-type ZnO nanowires and n-type ZnO thin films. The diodes exhibit highly stable lasing at room temperature, and can be modelled with finite-difference time-domain methods.