An amorphous silicon a-Si:H thin film transistor (TFT), which has (i) two separate channels vertically stacked; (ii) two gate electrodes, i.e., one on the top and the other one at the bottom, and (iii) a self-aligned source/drain to bottom gate structure, is presented and studied. This TFT is not sensitive to light illumination because the channels are enclosed by two opaque gate electrodes. It has an I-off less than 10(12) A, an I-on/I-off ratio greater than 10(6), and a subthreshold slope of 0.42 V/decade. When both gate electrodes are driven, the value of I-on is higher than the sum of the two separate values of I-on corresponding to each gate electrode driven individually. The high performance of the two-channel TFT is due to the field enhancement from both the top and the bottom gates.