METHOD FOR MAKING A PHOTO-TRANSFORMER Russian patent published in 2007 - IPC H01L31/18 

FIELD: technology for making devices, transforming light to electric energy.

SUBSTANCE: method for making photo-transformer on semiconductor plate with structure n-Ge substrate, n-GaAs buffer layer, n-GaAs base layer, p-GaAs emitter layer, p⁺-GaAlAs wide-zone layer, p⁺-GaAs contact layer, includes spraying contact metallization layer onto back of plate, forming protective photo-resist layer, growing of back contact by electro-chemical sedimentation of silver, removal of photo-resist, serial spraying of contact metallization layers of chromium 200÷400Å thick, of palladium 200÷500Å thick, of silver 500÷1500Å thick, creation of photo-resistive mask with pattern of contacts, growing of contact by electro-chemical sedimentation of silver, removal of photo-resist, etching together of sprayed layers of contact metallization by means of ion-beam etching, thermal processing of plate, creation of photo-resistive mask with pattern of windows along perimeter of photo-transformer, etching of gallium arsenide layers up to germanium layer, removal of photo-resist, etching together of layers of p⁺-GaAs layer beyond limits of contact areas and application of anti-reflecting cover. After spraying of contact metallization layer onto back, thermal processing of plate is performed and sprayed serially are contact metallization layers of chromium at temperature of 300÷350Å, palladium and silver at temperature of 200÷250Å. After removal of photo-resistive mask with contact pattern, layers of silver and palladium are etched together by means of ion-beam etching up to layer of chromium, further layer of chromium is removed in water solution of hydrochloric acid, and after etching of gallium arsenide layers up to germanium substrate and removal of photo-resist, p⁺-GaAs layer is etched together beyond limits of contact areas in water solution of lemon acid, lemon-acidic potassium and hydrogen peroxide at temperature of 40÷50°C.

EFFECT: improved quality of face contacts of transformer due to increased adhesion and decreased transfer resistance.

4 dwg