High electric-field amorphous silicon p-i-n diodes: Effect of the p-layer thickness

We present amorphous silicon p-i-n diodes able to sustain a reverse bias corresponding to 106 V/cm with a reasonably low leakage current. The influence of the p-layer thickness on the reverse bias current and the breakdown voltage is investigated. The high-voltage reverse current at room temperature is attributed to two different mechanisms: field enhanced thermal generation in the p-i interface region and, at the highest bias, electron injection through the p layer. Variable range hopping is also contributing to the low-temperature reverse current. Charge collection measurements after pulsed photogeneration were also performed up to the maximum voltage. No evidence for signal amplification is found, which sets a lower limit of 106 V/cm for impact ionization and avalanche phenomena.