Improvement of Electronic Transport Characteristics of Amorphous Silicon by Hydrogen Dilution of Silane

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Abstract
We have investigated the electrical and material properties of intrinsic amorphous silicon deposited with hydrogen dilution of silane. The hydrogenated material was used as intrinsic layers of n-i-p diodes, which showed interesting electrical characteristics. From time of flight (TOF) measurement for our best samples produced at hydrogen to silane ratio of 15, we obtained mobility (µ) values about 3-4 times larger than our standard amorphous silicon (a-Si:H). Approximately a factor of 2 improvement was observed for µτ values. The N D * values of the hydrogen diluted a-Si:H were measured for the first time and show lower ionized dangling bond density than the normal a-Si:H material. At a hydrogen to silane gas flow ratio of 20, some microcrystalline formation was observed in the deposited material. We propose a simple macroscopic model to assess the effect of microcrystals and grain boundaries on the electronic properties of mixed amorphous and microcrystalline material.