Thin film transistors (TFTs) of indium oxide (In2O3) and tin oxide (SnO2) were fabricated on SiO2 gate dielectric using reactive evaporation process. Structural investigation of the films revealed that In2O3 films were polycrystalline in nature with preferred (222) orientation and SnO2 films exhibited amorphous nature. The x-ray photoelectric spectroscopy measurements suggest that SnO2 films were oxygen rich and presume mixed oxidation states of Sn, namely Sn2+ and Sn4+. While the In2O3 based TFTs possess n-type channel conduction, SnO2 based TFTs exhibited anomalous p-type conductivity. Integration of these n- and p-type devices resulted in complementary inverter with a gain of 11.

The influences of doping densities at the quantum-dot (QD) region for 30-period InAs∕GaAs quantum-dot infrared photodetectors (QDIPs) are investigated. The InAs∕GaAs QDIPs with a lower doping density can operate at high responsivity and high background-limited-performance temperature. Also observed is the decreasing photocurrent ratio of s∕p-polarized lights for the QDIPs with increasing QD doping density. Compared to the similar photocurrent ratio of s∕p-polarized lights for the GaAs∕AlGaAs quantum-well infrared photodetectors at different applied voltages, the observed voltage-dependent response ratio for QDIPs is attributed to the strong scattering characteristics of QDs occupied with photoexcited electrons for electron transport through the QD region.

In this article, we report the fabrication of SnO 2 thin film transistors ͑TFTs͒ fabricated by reactive evaporation. Different from the previous reports, the fabricated TFTs exhibit p-type conductivity in its undoped form. The postdeposition annealing temperature was tuned to achieve p-channel SnO 2 TFTs. The on/off ratio and the field-effect mobility were ϳ10 3 and 0.011 cm 2 / V s, respectively. To demonstrate inverter circuit, two devices with different threshold voltages were combined and an output gain of 2.8 was achieved. The realization of p-channel oxide TFTs would open up new challenges in the area of transparent electronics.

The temperature dependence of photoluminescence from the high-quality unintentionally doped GaSb layers grown by liquid-phase epitaxy has been studied. The epitaxial layers grown at temperatures above 590 °C, from the Ga- or Sb-rich solutions, reproducibly have a low-carrier concentration of 6–8×1015 cm−3 and exhibit p-type conduction. But it gives n type as grown from the Ga-rich solution at 360 °C. For the samples grown from the Ga-rich solutions, the 16 K photoluminescence spectrum is dominated by the partially resolved lines related to the transitions of excitons bound to donors and neutral acceptors. The acceptor-related band (777.8 meV) which is always presented in the GaSb material due to the native lattice defects has been much reduced as compared to the exciton-related lines. Especially for the n-type samples grown at low temperatures (360 °C), the ratio of the emission intensity from the exciton-related lines to that from the acceptor-related band is 10. For the samples grown from the Sb-rich solutions, the 16 K photoluminescence spectrum is also dominated by a bound exciton-related line with a full width at half maximum of 4.2 meV. In addition, the free-exciton transition with a full width at half maximum of 0.4 meV is also observed. As the temperature is increased, the intensity of the lines associated with the bound excitonic transitions for all the GaSb samples rapidly quenches off and the free-electron-to-free-hole transition becomes dominant. The temperature dependent band gap in GaSb layers determined from the photoluminescence peak energy varies as 0.813–[1.08×10−4 T2/(T−10.3)] eV.