Combined effects of cycling endurance and total ionizing dose on floating gate memory cells

The combined effects of cycling endurance and radiation on floating gate memory cell are investigated in detail,and the obtained results are listed below.(i)The programmed flash cells with a prior appropriate number of program and easing cycling stress exhibit much smaller threshold voltage shift than without those in response to radiation,which is ascribed mainly to the recombination of trapped electrons(introduced by cycling stress)and trapped holes(introduced by irradiation)in the oxide surrounding the floating gate.(ii)The radiation induced transconductance degradation in prior cycled flash cell is more severe than those without cycling stress in the programmed state or erased state.(iii)Radiation is more likely to set up the interface generation in programmed state than in erased state.This paper will be useful in understanding the issues involved in cycling endurance and radiation effects as well as in designing radiation hardened floating gate memory cells.

Analysis on degradation mechanisms of normally-off p-GaN gate AlGaN/GaN high-electron mobility transistor

The degradation mechanisms of enhancement-mode p-GaN gate AlGaN/GaN high-electron mobility transistor was analyzed extensively,by means of drain voltage stress and gate bias stress.The results indicate that:(ⅰ) High constant drain voltage stress has only a negligible impact on the device electrical parameters,with a slightly first increase and then decrease in output current;(ⅱ) A negative shift of threshold voltage and increased output current were observed in the device subjected to forward gate bias stress,which is mainly ascribed to the hole-trapping induced by high electric field across the p-GaN/AlGaN interface;(ⅲ) The analyzed device showed an excellent behavior at reverse gate bias stress,with almost unaltered threshold voltage,output current,and gate leakage current,exhibiting a large gate swing in the negative direction.The results are meaningful and valuable in directing the process optimization towards a high voltage and high reliable enhanced AlGaN/GaN high-electron mobility transistor.