A new source of cadmium diffusion in In0.53Ga0.47As has been developed. Langmuir–Blodgett (LB) deposited monolayers of cadmium arachidate have been used as a source of cadmium. The LB film has been characterized by grazing incidence infrared spectroscopy and Auger electron spectroscopy. Acceptor profiles obtained by differential Hall technique are presented. Highly doped (NA=2×1019cm−3) shallow (xj≊0.1–0.4 &mgr;m),p+‐njunctions are obtained. Mesa‐typep‐i‐ndiodes with 125 &mgr;m diameter, ideality factor =1.3,Idark=5 nA at 20 V reverse bias, andVbreakdown=30 V have been fabricated.