Hu Lizhong

Al0.3Ga0.7As microtips grown by self-assembled LPE for integrated SNOM sensors

Abstract An improved technique for manufacturing Al0.3Ga0.7As microtips grown by self-organized liquid phase epitaxy (LPE) for a novel kind of integrated Scanning near-field optical microscopy (SNOM) sensors is reported. Scanning electron microscopy pictures show high apex quality of the tips. The future scope of batch monolithic integration of the SNOM sensor array by compound techniques of molecular beam epitaxy (or metal-organic chemical vapor deposition) and LPE is also discussed.

Effect of Different Substrate Temperature on Sb-Doped ZnO Thin Films Prepared by Pulsed Laser Deposition on Sapphire Substrates

Sb-doped ZnO thin films are deposited on c-plane sapphire substrates by pulsed laser deposition. Hall results indicate that the conductivity of the Sb-doped ZnO thin films is strongly dependent on the substrate temperature. The sample deposited at the temperature of 550°C exhibits p-type conductivity. It gives a resistivity of 15.25 Ω cm, with a Hall mobility of 1.79cm2V−1s−1 and a carrier concentration of 2.290 × 1017 cm−3 at room temperature. The x-ray diffraction indicates that the Sb-doped ZnO thin films deposited in the range of 450–650°C are high c-axis oriented. Low-temperature photoluminescence spectra indicate that the sample deposited at 550°C shows the strong acceptor-bound exciton (A0X) emission.

Luminescence properties of ZnS:Cu, Eu semiconductor nanocrystals synthesized by a hydrothermal process

ZnS:Cu, Eu nanocrystals with an average diameter of ~ 80 nm are synthesized using a hydrothermal approach at 200 °C. The photoluminescence (PL) properties of the ZnS:Cu, Eu nanocrystals before and after annealing, as well as the doping form of Eu, are studied. The as-synthesized samples are characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, and the excitation and emission spectra (PL). The results show that both Cu and Eu are indeed incorporated into the ZnS matrix. Compared with the PL spectrum of the Cu mono-doped sample, the PL emission intensity of the Cu and Eu-codoped sample increases and a peak appears at 516 nm, indicating that Eu3+ ions, which act as an impurity compensator and activator, are incorporated into the ZnS matrix, forming a donor level. Compared with the unannealed sample, the annealed one has an increased PL emission intensity and the peak position has a blue shift of 56 nm from 516 nm to 460 nm, which means that Eu3+ ions reduce to Eu2+ ions, thereby leading to the appearance of Eu2+ characteristic emission and generating effective host-to-Eu2+ energy transfer. The results indicate the potential applications of ZnS:Cu, Eu nanoparticles in optoelectronic devices.