Method for fabricating an optical controlled resonant tunneling oscillator

A method for fabricating an optically controlled resonant tunneling oscillator comprising the steps:

• successively growing a buffer layer made of n.sup.+ -type GaAs, first and second spacer layers, a first barrier layer, a well layer and a second barrier layer having a double quantum well, third and fourth spacer layers, and a window layer over a semi-insulated substrate made of GaAs with a molecular beam epitaxy growth;
• mesa-etching the window layer to a portion of the buffer layer using a photoresist pattern as a mask, thereby forming a mesa structure and exposing the buffer layer;
• forming openings of a photoresist on the mesa structure and an exposed buffer layer so as to form electrodes;
• depositing a multi-metal of AuGe/Ni/Au over a surface and then subjecting the multi-metal to a lift off processing;
• etching the exposed buffer layer and a portion of the underlying substrate except for the mesa structure and the openings, so as to isolate the oscillator;
• depositing an insulation layer over a whole surface of the substrate;
• etching the insulation layer using a photoresist pattern as a mask, thereby forming contact holes on the multi-metal;
• forming metal patterns for a bonding pad on the contact holes;
• and
• performing annealing of optically controlled resonant tunneling oscillator after completion of all photo-etching.