METHOD OF MAKING OHMIC CONTACT TO GaAs Russian patent published in 2012 - IPC H01L21/28 B82B3/00 

FIELD: physics.

SUBSTANCE: in the method of making an ohmic contact to GaAs, a mask is formed on the surface of an n-GaAs plate, having a doped layer, in order to carry out a lift-off lithography process. To clean the surface in the windows of the mask, the n-GaAs plate is treated in aqueous H₂SO₄ or HCl solution and then washed in deionised water and dried. Further, via electron-beam and/or thermal evaporation in a vacuum at residual pressure lower than 5x10^-6 torr, Ge and Cu are deposited with total thickness of 100-500 nm and weight content of germanium in the double-layer composition equal to 20-45%. Further, in a single vacuum cycle, the n-GaAs plate undergoes first thermal treatment at temperature T₁=150-460°C in an atmosphere of atomic hydrogen with hydrogen atom flux density on the surface of the plate equal to 10¹³-10¹⁶ at.cm² s^-1. The n-GaAs plate is removed form the vacuum chamber, and after removing the mask, undergoes second thermal treatment in an atmosphere of an inert gas or in a vacuum at temperature T₂=280-460°C for t=0.5-30 min.

EFFECT: lower value of reduced contact resistance.

2 cl, 1 dwg