COMPUTER STUDIES OF QUASI READ GALLIUM-ARSENIDE IMPATT DIODE - INCLUDING THE EFFECT OF SPACE-CHARGE

Computer studies have been carried out on the effects of variation of impurity hump parameters of quasi Read high-low (hi-lo) and low-high-l ow (lo-hi-lo) gallum arsenide IMPATT diodes on their DC and microwave properties. The effect of mobile space charge has been included in the computer analysis. It turns out that the DC properties of the diode a re sensitive functions of the width and doping concentration of impuri ty bumps. The optimum efficiency is found to be respectively 24.5% and 27.9% for hi-lo and lo-hi-lo diodes designed for 18 GHz frequency. Th e small signal admittance calculations show that a lo-hi-lo structure provides higher negative conductance and better quality factor compare d with a hi-lo structure of CaAs Impatt diode.