ELECTRONIC EFFECTS OF ION MOBILITY IN SEMICONDUCTORS - SEMIONIC BEHAVIOR OF CUINSE2

Application of strong electric fields at ambient temperatures to cryst als of CuInSe2 and (Cu,Ag)InSe2 semiconductors can create non-equilibr ium doping profiles, stable after removal of the electric field, as il lustrated by formation of mu m-sized single and multiple diode structu res in initially homogeneous and uniformly doped single crystals. Phot otransistor action and amplification was obtained, clear evidence for the presence of junctions, resulting from non-equilibrium doping profi les. Electron beam-induced current measurements, combined with current -voltage, capacitance-voltage and time-dependent current measurements, as well as numerical simulations were performed to characterize and u nderstand the phenomena. Control experiments exclude formation of exte nded defects or the occurrence of contact diffusion. Localized Joule h eating that occurs around the contact cannot by itself account for the observed phenomena. Because these chalcopyrites contain relatively mo bile components [Cu,Ag], which are also dopants, we interpret these ob servations as a result of internal dopant redistribution, aided by loc alized temperature increases and directed by the electric field.