Effect of high-energy electron beam irradiation on the properties of ZnO thin films prepared by magnetron sputtering A comparative analysis of deep level emission in ZnO layers deposited by various methods ZnO nanowire NW growth mechanism was investigated in a nonvapor and noncatalytic approach for the controlled NW synthesis in a second time scale. The experimental results showed what ZnO NW growth was determined by migration of zinc interstitials and vacancies in a ZnO layer, which should be also considered in other synthesis techniques and mechanisms. The mechanism of the ZnO NW growth was explained as due to the advantageous diffusion through grain boundaries in ZnO layer and crystal defects in NWs. Additionally, on the basis of photoluminescence measurements, a feasible application of as-produced wires for optoelectronic devices was demonstrated.

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V-defect formation of the In x Ga 1Ϫx N/GaN multiple quantum wells ͑MQWs͒ grown on GaN layers with different threading dislocation ͑TD͒ densities was investigated. From cross-sectional transmission electron microscopy, we found that all V defects are not always connected with TDs at their bottom. By increasing the indium composition in the In x Ga 1Ϫx N well layer or decreasing the TD density of the thick GaN layer, many V defects are generated from the stacking mismatch boundaries induced by stacking faults which are formed within the MQW due to the strain relaxation. Also, TD density in the thick GaN layer affects not only the origin of V-defect formation but also the critical indium composition of the In x Ga 1Ϫx N well on the formation of V defects.

Cu2O thin films were synthesized on Si (100) substrate with thermally grown 200-nm SiO2 by sol-gel spin coating method and postannealing under different oxygen partial pressure (0.04, 0.2, and 0.9 Torr). The morphology of Cu2O thin films was improved through N2 postannealing before O2 annealing. Under relatively high oxygen partial pressure of 0.9 Torr, the roughness of synthesized films was increased with the formation of CuO phase. Bottom-gated copper oxide (CuxO) thin film transistors (TFTs) were fabricated via conventional photolithography, and the electrical properties of the fabricated TFTs were measured. The resulting Cu2O TFTs exhibited p-channel operation, and field effect mobility of 0.16 cm2/(V s) and on-to-off drain current ratio of ∼1×10(2) were observed in the TFT device annealed at PO2 of 0.04 Torr. This study presented the potential of the solution-based process of the Cu2O TFT with p-channel characteristics for the first time.

Multi-valued logic gates are demonstrated on solution-processed molybdenum disulfide (MoS2) thin films. A simple chemical doping process is added to the conventional transistor fabrication procedure to locally increase the work function of MoS2 by decreasing sulfur vacancies. The resulting device exhibits pseudo-heterojunctions comprising as-processed MoS2 and chemically treated MoS2 (c-MoS2). The energy-band misalignment of MoS2 and c-MoS2 results in a sequential activation of the MoS2 and c-MoS2 channel areas under a gate voltage sweep, which generates a stable intermediate state for ternary operation. Current levels and turn-on voltages for each state can be tuned by modulating the device geometries, including the channel thickness and length. The optimized ternary transistors are incorporated to demonstrate various ternary logic gates, including the inverter, NMIN, and NMAX gates.