Glow Discharge Amorphous Silicon Tin Alloys

We present basic density of states, photoresponse, and transport measurements made on low bandgap a-SiSn:H alloys produced by RF glow discharge deposition of SiH4, R, and Sn(CH3)4. Although we demonstrate major changes in the local bonding structure and the density of states, the normalized photoresponse still remains poor. We provide evidence that two types of defect levels are produced with Snalloying, and that the resultant density of states increase explains not only the n-to p?-type conductivity transition reported earlier, but also the photo response behavior. We also report that a-SiSn:H can be doped with P. From our device analysis we suggest that in order to improve the alloy performance significantly, the density of states should be decreased to levels comparable to or lowerthan those presently obtained in a-Si:R.