Microcrystalline Silicon Thin-Film Transistors for Ambipolar and CMOS Inverters

Microcrystalline silicon (mu c-Si:H) thin-film transistors (TFTs) have lately gained much attention due to their high charge carrier mobilities. We report on top-gate mu c-Si:H TFTs fabricated by plasma-enhanced chemical vapor deposition at process temperatures below 180 degrees C with high electron and hole charge carrier mobilities exceeding 50 cm(2)/Vs and 12 cm(2)/Vs, respectively. Based on the mu c-Si:H TFTs different thin-film inverters were realized including ambipolar and complimentary metal-oxide-semiconductor (CMOS) inverters. Microcrystalline CMOS inverters exhibit high voltage gains exceeding 22, whereas ambipolar inverters show reduced voltage gains of 10 at low operating voltages. The electrical characteristics of the mu c-Si:H CMOS and ambipolar thin-film inverters will be discussed in terms of the voltage transfer curve, the voltage gain and the power dissipation.