Mott barrier behavior by enhanced donorlike level neutralization in semi-insulating GaAs Schottky diodes

The Mott barrier behavior of metal-semi-insulating GaAs diodes is explained by the compensation mechanism due to bulk donorlike centers. In such diodes the quasineutral region extends from metallization to a buried space charge region and widens with increasing bias. To assess the dependence of this behavior on the electronic levels associated with bulk deep donors, their density was increased by proton irradiation. We observed that the net space-charge density decreases and, correspondingly, the quasineutral region extent increases. The correlation between electric field distribution and deep levels confirms the strong influence of defects on the compensation process.