Insulator-semiconductor interface charge trapping

Note that this is a very simplified case. A liquid junction, dual-layer insulator, trapped charges in the insulator, surface states at the insulator/semiconductor interface, channel doping profile, and multiple connecting metals have been omitted, for the sake of simplicity. They would be present in all real devices and situations, but would not affect the thought analysis in any significant way. 

Interface states played a key role in the development of transistors. The initial experiments at Bell Laboratories were on metal/insulator/semiconductor (MIS) stmctures in which the intent was to modulate the conductance of a germanium layer by applying a voltage to the metal plate. However, only - 10% of the induced charges were effective in charging the conductance (3). It was proposed (2) that the ineffective induced charges were trapped in surface states. Subsequent experiments on surface states led to the discovery of the point-contact transistor in 1948 (4). 

To reduce the problem of interface states which may trap signal charge in a CCD, it is proposed in JP-A-57169278 to use an epitaxially grown cadmium telluride layer as an insulator between the transfer electrodes and an HgCdTe semiconductor layer. 

Only recently it has been discovered that electronic states at the dielectric interface substantially determine the charge carrier transport in organic field-effect transistors. Pentacene is a prominent example where the unique p-type behavior of pentacene based OFETs has been attributed to the organic semiconductor alone and where the influence of electronic interface states at the pentacene/insulator surface has been overseen. The reason for this was the belief that organic semiconductors are unable to form dangling bonds at the interface, which are the main cause for interface states in inorganic semiconductors. However, there are other forms of interface states which can act as efficient charge carrier traps. 

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