Effect of low-temperature annealing on the quality of InSe layered single crystals and the characteristics of n-InSe/p-InSe heterojunctions

The effect of the low-temperature annealing of n - and p -type InSe single crystals on the photoelectric characteristics of n -InSe/ p -InSe heterojunctions is investigated. It is found that the most pronounced enhancement of these characteristics takes place for annealing temperatures of 150–200°C. Improvement in the quality of single-crystal samples upon annealing is confirmed by the observation of multiplet nuclear quadrupole resonance spectra, which reflect ordering in the system of polytypes of layered InSe crystals. For annealed materials, n -InSe/ p -InSe structures exhibit an increase in the intensity of the exciton peak and an increase in the open-circuit voltage from 0.29 to 0.56 V and short-circuit current from 350 to 840 μA/cm 2 .