SPACE-CHARGE-LIMITED INJECTION IN N(-I-N(+) STRUCTURES FABRICATED BY A FOCUSED ION-BEAM())

Transport characteristics of n(+)-i-n(+) structures fabricated on a Ga As/AlGaAs HEMT wafer are presented. An insulating strip (i) between tw o-dimensional electron gases (n(+)) is created by a single line scan o f a focused ion beam. At sufficiently large biases, the current-voltag e (I-V) characteristics of the n(+)-i-n(+) structures display highly l inear increases of the currents as a function of the biases. The obser ved I-V's are quantitatively explained by the space-charge limited inj ection into the insulating region when the bias is large enough for th e flatband condition. The charged defect density and the length of the insulating region are obtained from the I-V characteristics. (C) 1995 American Institute of Physics.