Single-electron effects in side-gated point contacts fabricated in low-temperature deposited nanocrystalline silicon films

Single-electron effects have been observed up to 60 K in a side-gated point contact device fabricated in nanocrystalline silicon films. The films were phosphorus-doped and deposited at 300 °C by plasma enhanced chemical vapor deposition. Using transmission electron microscopy and Raman spectroscopy, the grain size, crystalline volume fraction, and grain boundary thickness are determined. The single-electron effects are associated with islands formed by crystalline silicon grains ∼4 nm in size, isolated by amorphous silicon regions ∼0.5 nm in thickness. The structural characteristics of the nc-Si film are correlated to the electrical behavior. The electrical transport mechanism at high temperatures is attributed to percolation conduction across a distribution of tunnel barriers with a maximum height of 40 meV.