Amorphous silicon transistors on ultrathin steel foil substrates

Thin-film transistors of hydrogenated amorphous silicon (a-Si:H) were fabri cated on foils of stainless steel with thickness ranging down to 3 mu m, wh ich is less than three times the thickness of the deposited films. Transist ors made on foils from 3 to 200 mu m thick exhibit comparable electrical pe rformance. Two factors account for the feasibility of such thin device/subs trate structures. One is that the built-in stress and the differential ther mal contraction stress nearly cancel each other in steel/a-Si:H structures. The other is that on very thin foils the transistor structure offloads par t of its strain to the steel foil. (C) 1999 American Institute of Physics. [S0003-6951(99)04118-2].