The effects of a hydrogen ambient on the interface state energy distribution of gamma irradiated and charge injected metal-oxide-semiconductor structures fabricated on germanium/boron doped silicon

Abstract

The effects of a hydrogen ambient on the change in interface state energy distribution of germanium/boron (Ge/B) counterdoped silicon substrate metal-oxide-silicon capacitor structures during and following gamma irradiation were investigated. The presence of hydrogen during irradiation produces both a significantly larger increase in interface state density throughout the band gap and a higher peak value at approximately 0.7 electron volts above the valence band (0.7-eV peak) than is obtained for devices irradiated in air. Additionally, the time for the 0.7-eV peak to reach its maximum value is much shorter as is the time lapse for the initiation of growth of a trap peak at 0.35 electron volts above the valence band (0.35-eV peak). Devices irradiated in air and then stored in hydrogen exhibit similar behavior as those irradiated in hydrogen except that the interface state buildup with time is much slower. Pretreating devices by exposure to hydrogen prior to Fowler–Nordheim (F-N) injection or avalanche electron injection (AEI) is shown to inhibit interface state generation including a significant reduction in the 0.7-eV peak height. This result suggests that hydrogen created by F-N injection and AEI passivate dangling bonds associated with germanium in the silicon.