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The article studies the current-voltage mechanism of low-ideality factor ZnO Schottky diodes over temperature range of 40-423 K. Findings revealed that TE was a major current transport mechanism at RT and above.

A Solid-state Impact-ionization Multiplier (SIM) design that injects electrons into the SIM's depletion region through a p-n junction node instead of through a Schottky contact as in previous versions is proposed. It is observed that the measured gain characteristics are similar to simulated results, and measured frequency response could improve the SIM's performance with lower currents inputs.

Several experimental and computational studies are conducted to determine the forward current density ([J.sub.F])-forward voltage ([V.sub.F]) characteristics of 4H-silicon junction barrier Schottky (JBS) diodes. These characteristics are shown to be highly affected by the lateral spreading of the implanted aluminum ions and implantation-induced defects.

The performance of 4H-SiC planar junction barrier Schottky (JBS) rectifiers and lateral channel JBS (LC-JBS) rectifiers is described. The lateral channel JBS rectifier is designed and demonstrated in 4H-SiC with up to 1.5-kV blocking capability and pinlike reverse characteristics.

The 4H-SiC floating junction (FJ) Schottky barrier diodes (SiC Super-SBDs) are examined. The structural parameters are optimized by making improvements in the device simulation and by developing the device fabrication process.

4H-SiC Junction Barrier Schottky (JBS) diodes are processed by using the same technology with two different layouts. Electroluminescence measurements have displayed the expansion of stacking faults in 3.5 kV diodes unlike in 1.2-kV diodes.

The forward and reverse bias dc characteristics, the long-term stability under forward and reverse bias and the reverse recovery performance of 4H-SiC junction barrier Schottky (JBS) diodes that are capable of blocking in excess of 10 kV with forward conduction of up to 10 A at a forward voltage of less than 3.5 V are described. The diodes have shown a positive temperature coefficient of resistance and a stable Schottky barrier height of up to 200 degree centigrade.

The diode characteristics at 2.45 and 35 GHz and the use of a frequency selective surface are investigated for the application of microwave power transmission. A method has been devised to experimentally characterize a packaged GaAs Schottky barrier diode by inserting in a microstrip test mount. The nonlinear equivalent circuit parameters of the diode are determined by a small signal test method. The method analyzes the diode's scattering parameters at various bias levels. A large signal measurement using the same test mount has also been configured to determine the power conversion efficiency from microwave to dc as well as determining the de-embedded network impedance of the diode. A nonlinear circuit simulation program using a multi-reflection algorithm is used to verify the experimental results of a 2.45 GHz diode. A Ka-band mixer diode is also simulated for a 35 GHz rectenna. Based on the simulation results, a patch-type 35 GHz rectenna is designed and tested in a waveguide simulator. The efficiency is measured as 29% with a 120 mW input power. Because the diode could generate undesirable harmonic radiation, a frequency selective surface is designed to reduce the second harmonic radiation for a 2.45 GHz rectenna. Theoretical results agree fairly well with experiments for all these studies.

The diode characteristics of heterojunction diodes are examined which consists of a crystalline semiconductor material such as ZnO covered with a thin semiconducting film of amorphous or disordered material. The studies have shown that heterojunctions displaying large ideality factors n > 2 has possessed an interfacial disordered or amorphous layer with Frenkel-Poole conduction properties.

A study on x-ray detectors based on GaN Schottky diodes fabricated based on a 20 [mu]m thick undoped GaN layer grown on a conductive GaN substrate is presented. A very strong quenching of the x-ray photoresponse observed when the detector is simultaneously illuminated with visible light explain theanomalous behavior in the frame of a complete model involving traps and tunnel currents.

The effects of premetallization annealing on the electrical characteristics of GaN and [Al.sub.x][Ga.sub.1-x]N Schottky diodes are analyzed. The studies have shown that the Pt/Au Schottky contacts on the annealed GaN became leakier, whereas those on the thermally damaged AlGaN have displayed more rectifying characteristics.

The changes in the electrical properties of 4H-SiC epitaxial layer induced by irradiation with 7.0 MeV [C.sup.+] ions are examined by current-voltage measurements and deep level transient spectroscopy (DLTS). DLTS measurements of the irradiated diodes have disclosed the presence of two deep levels located at 0.98 and 1.4 eV below the conduction band edge.

The forward and reverse bias current-voltage (I-V) characteristics of Al/Si[O.sub.2]/p-Si (metal-insulator-semiconductor) type Schottky diodes (SDs) are measured in a wide temperature range. The studies have shown that the temperature dependence of the forward bias I-V characteristics of the Al/Si[O.sub.2]/p-Si SDs is described based on the thermionic emission mechanism with a Gaussian distribution (GD) of the barrier heights (BHs).