Effects of electron confinement on thermionic emission current in a modulation doped heterostructure

We discuss mechanisms responsible for the reduction of electron thermionic emission current from a Schottky contact to a modulation doped semiconducto r compared to a bulk semiconductor. The effects discussed include metal to semiconductor barrier height enhancement due to proposed electron-electron cloud interaction, confined potential of the reduced dimensional systems, a nd the reduced dimensional nature of the density of states in the semicondu ctor. These effects describe the observed lowering of the dark current, and hence noise, of a modulation doped heterojunction based photodetector comp ared to a conventional bulk device. (C) 1999 American Institute of Physics. [S0021-8979(99)04605-8].