AFM study of charging of the Au–n-GaAs contact

• The effect of local changing of contact potential difference of Au–GaAs with charging is detected.
• It is assumed that the CPD change is due to the charge trapping at the metal–semiconductor interface.
• Local charging causes increasing of the etch rate of the metal film.
• The relief modification can have practical importance as a new maskless lithography method.

Effect of charging of structural elements of a metal–semiconductor Au–n-GaAs contact on the behavior of the contact potential difference (CPD) and other properties of the contact is investigated by AFM method. The change of the CPD caused by charging reaches the values of ∼0.5 V and depends on the bias value, duration of exposure, scanning speed, and thickness and area of the metal. It is assumed that the above change is mainly due to the accumulation of an induced charge at the metal–semiconductor interface. However, it is not excluded that accumulation of charge occurs also at the grain boundaries of the metal. This is evidenced by the changes in properties of the gold film caused by charging: the rate of the film etching increases. This makes it possible to form a relief on the surface of the metal, which is set by the mode of the probe scanning over the surface of the metal during charging.

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