Post-Growth Technology of Multi-Junction Photovoltaic Converters Based on A3B5 Heterostructures

Investigation and development of the post-growth technology for fabricating multi-junction photovoltaic converters based on GaInP/GaInAs/Ge heterostructure has been carried out. Antireflection coating, ohmic contacts and mesa- structure forming stages have been reviewed. The technology of n⁺-GaAs contact layer etching with the help of plasma-chemical, liquid and ion-beam etching has been investigated. Antireflection coefficient of radiation from the heterostructure with TiO_x/SiO₂ (x close to 2) antireflection coating surface was less then 3% in wavelength range 450–850 nm. The value of contact resistance for n- and p-type conductivity was 3 × 10^–5–3 × 10^–6 Ω cm², the decrease of photosensitive region shading degree at increased bus-bar conductivity has been archived. The mesa-structure surface current leakage decreased to the value of 10^–9 A at voltage less then 1 V.