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The contact characteristic between p-InP and metal plays an important role in InP-related optoelectronic and microelectronic device applications. We investigate the low-resistance Au/Pt/Ni and Au/Ni ohmic contacts to p-InP based on the solid phase regrowth principle. The lowest specific contact resistivity of Au(100 nm)/Pt(115 nm)/Ni (50 nm) can reach 2.64 × 10−6 Ω ⋅ cm2 after annealing at 380 °C for 1 min, while the contact characteristics of Au/Ni deteriorated after annealing from 340 °C to 480 °C for 1 min. The results of scanning electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy show that the Pt layer is an important factor in improving the contact characteristics. The Pt layer prevents the diffusion of In and Au, inhibits the formation of Au3In metal compounds, and prevents the deterioration of the ohmic contact. The metal structures and optimized annealing process is expected to be helpful for obtaining high-performance InP-related devices.

Photoluminescence (PL) plays an important role in the study of luminescence characteristics of multi-quantum-well (MQW) structures. In this work, we study electro-photoluminescence spectra of InGaAs/AlGaAs MQWs under open-circuit, short-circuit, and forward-voltage conditions. The dependences of photocurrent and photovoltage on excitation power are discussed in this paper, which allows us to explore the carrier behavior in InGaAs/AlGaAs MQW LEDs deeply. We propose that the photovoltaic effect in open-circuit (OC) conditions should be properly considered for PL characterization and calculation of the internal quantum efficiency (IQE) as well as non-radiative recombination (NRA) efficiency in InGaAs/AlGaAs MQW LEDs.

It is known that the p–n junction of an absorption region is a crucial part for power conversion efficiency of photovoltaic power converters. We fabricate four samples with different dopant concentrations in base layers. The dependences of power conversion efficiency and fill factor on input power are displayed by photocurrent–voltage measurement. Photoluminescence characteristics under open circuit and connected circuit conditions are also studied. It is found that the status of p–n junction matching is the critical factor in affecting the power conversion efficiency. In addition, series resistance of photovoltaic power converters impairs the efficiency especially at high input powers. Both the key factors need to be considered to obtain high efficiency, and this work provides promising guidance on designing photovoltaic power converters.

We have successfully prepared GaN based high electron mobility transistors (HEMTs) on metallic substrates transferred from silicon substrates by electroplating technique. GaN HEMTs on Cu substrates are demonstrated to basically have the same good electric characteristics as the chips on Si substrates. Furthermore, the better heat dissipation of HEMTs on Cu substrates compared to HEMTs on Si substrates is clearly observed by thermoreflectance imaging, showing the promising potential for very high-power and high-temperature operation. This work shows the outstanding ability of HEMT chips on Cu substrates for solving the self-heating effect with the advantages of process simplicity, high yield, and low production requirement.

We report a type of thin film AlGaInP red light emitting diode (RLED) on a metallic substrate by electroplating copper (Cu) to eliminate the absorption of GaAs grown substrate. The fabrication of the thin film RLED is presented in detail. Almost no degradations of epilayers properties are observed after this substrate transferred process. Photoluminescence and electroluminescence are measured to investigate the luminous characteristics. The thin film RLED shows a significant enhancement of light output power (LOP) by improving the injection efficiency and light extraction efficiency compared with the reference RLED on the GaAs parent substrate. The LOPs are specifically enhanced by 73.5% and 142% at typical injections of 2 A/cm2 and 35 A/cm2 respectively from electroluminescence. Moreover, reduced forward voltages, stable peak wavelengths and full widths at half maximum are obtained with the injected current increasing. These characteristic improvements are due to the Cu substrate with great current spreading and the back reflection by bottom electrodes. The substrate transferred technology based on electroplating provides an optional way to prepare high-performance optoelectronic devices, especially for thin film types.

A general approach is presented for the controlled synthesis of large-scale Se/Te alloy nanowires (NWs) with sodium dodecylbenzene sulfonate (SDBS) as surfactant. It is found that SDBS acting as surfactant plays an important role in controlling the morphology of Se/Te products. The diameter of Se/Te NWs can be successfully controlled by changing the concentration of SDBS surfactant agents and by adjusting the dynamics of the reaction process. Uniform Se/Te nanoparticles (NCs) can be partly self-assembled into two-dimensional arrays when the SDBS concentration is up to 1.5 wt%. The reaction temperature and concentration of Se6+ and Te6+ in starting materials are also important parameters influencing the morphologies and phases of the final products. Phase structures, morphologies and optical properties of the Se/Te products are investigated by XRD, TEM, HRTEM and UV absorption spectroscopy. The formation mechanisms of the NWs and NCs are investigated and discussed on the basis of the experimental results.

A neatly controllable photonic band gap formed in a four-level tripod system in the solid material, Pr3+ -doped yttrium orthosilicate (Pr:YSO) is investigated. Driven by two standing waves, the sample is just like a photonic crystal to the weak probe. Based on the numerical simulation and the analytic result we present a clear and full-scale view on the induced band gap in the inhomogeneously broadened tripod system.

ZnO quantum dots (QDs) with blue emission were synthesized by a sol–gel method. A series of control experiments were conducted to explore the origin of the blue emission. It is found that the blue emission arises from neither the quantum confinement nor intermediate products, and it can be achieved only in the presence of Li+ cations and excessive OH− anions. Moreover, the long decay time of the blue emission suggests a defect-related de-excitation process. On the basis of the experimental and calculation results, possible de-excitation paths for light emission were discussed, and the origin of the blue emission was determined as the electron transition from the conduction band to interstitial oxygen defects. Excessive OH− anions are responsible for the formation of interstitial oxygen defects, and Li+ ions can stabilize the defects by substituting for Zn atoms. Besides, Li+ ions can block the growth of ZnO QDs, broaden their band gap and cause a blue shift of the blue emission.