A. A. Naik

Gate Leakage Current Suppression in AlGaN/GaN HEMT by RTP Annealing

Ni/Au Schottky contacts to AlGaN/GaN HEMT were formed by E-beam evaporation technique and lift-off process. The contacts were Rapid thermal annealed at 300 °C for duration of 2–10 min. A significant suppression in gate leakage current was observed at 2 and 4 min annealing. At further higher annealing duration deterioration in the reverse gate characteristics was observed.

(n)GaAs/Ti/Pt/Au Schottky contacts and their effect on MESFET's dc parameters

Abstract Rf sputtered Ti/Pt/Au Schottky contacts with varying titanium thickness have been made on (n)GaAs by the lift-off process under actual device processing conditions. The ideality factor of the Schottky barrier is dose to unity (∼ 1.07) with a barrier height of 0.80 ± 0.02 eV. The contacts with Ti films as thin as 100 A remain thermally stable with annealing up to 400°C. These contacts have been next used to fabricate submicron gate length GaAs MESFETs. The MESFETs gm increases with improved gate diode ideality but is not a strong function of it. The effect of Schottky gate annealing on the MESFETs dc characteristics shows that IDSS, gm, Vp and VR(GS) remain stable with annealing upto 350°C and degrade with 400° anneal.

Effect of Ni Ions Irradiation on GaAs pHEMT Materials and Devices

GaAs/AlGaAs heterostructure based pHEMT material and fabricated pHEMT devices characteristics were studied with Ni ions irradiation at different fluences. The structural, electrical and optical characteristics were compared before and after irradiation. The structural property of the material was found unchanged while optical and electrical deterioration was observed for used fluences.

Catalytic hydrogenation for improvement of GaAs/Ge solar cell efficiency

Abstract Hydrogen passivation on MOCVD grown p-GaAs epilayers on Ge substrate have been studied by plasma and catalytic hydrogenation and the results were compared. The conversion efficiency of the GaAs/Ge solar cells was found to increase by ∼10% after catalytic hydrogenation at AM1.5. This increase in efficiency is probably due to passivation of surface dangling bonds.

Fabrication of millimetre-wave Gunn and IMPATT devices with integral heat sink and integral bonding ribbon: a new approach

Abstract Discrete millimetre-wave devices, i.e. Gunn and IMPATT diodes, dissipate a large amount of power in the form of heat. Devices fabricated with an integral heat sink (IHS) are known to show superior performance compared with conventional devices. A novel process was developed for the fabrication of IHS integral bonding ribbon (IBR) millimetre-wave devices. The method employs “through holes” generated on the wafer as marks for “front to back” alignment of the IHS and IBR. The process is found to be highly reproducible and versatile. Devices have shown several advantages in terms of ease of processing and yield. The process can thus be used to fabricate devices different semiconductor materials and possibly for all devices requiring the IHS-IBR configuration.

Design And Fabrication Of GaAs 2-input Nor Gate

A GaAs 2-input NOR gate using the Buffered FET Logic approach has been designed, fabricated and tested. The logic gate has been simulated on SPICE 3 sofhvare for I GHz clock rate afrer taking into account the contributions due to parasitics and limitations in actual device processing. The layout of the circuit was designed ajer suitably modifring the AutoCAD KIO sofware to generate coordinates in the SPD (Source Pattern Data) format for direct mask fabrication by E-beam lithography. The circuit has been fabricated successfully by the fully planar selective implantation process and I um linewidth Ti/WAu gate metallisation. The DC and RF performance has been demonstrated experimentally and was found to match the simulated results.