Role of ion beams and their energies in the properties of zinc tin phosphide thin films

Abstract

Zinc tin phosphide (ZTP) is a promising low cost light sensing semiconductor material. The present study focuses on the effects of various ion beams having energies in the range of keV to MeV, on the structural, optical, and photo-response properties of ZTP thin films. Low energy ions (100 and 200 keV Al and Cu, 150 keV Fe and 60 keV Au ions) of fluences in the range from 1E13 to 1E16 ions/cm2 and high energy ions (80 MeV Si, 100 MeV Ni and 100 MeV Ag ions) from 1E11 to 6E13 ions/cm2 are used. The energy of ions (low or high) determine the changes in the ion-induced defects, structural disorder and recrystallization effects leading to modification in the structural quality, the evolution of microstructure, variation in the optical band gap (from 1.60 to 1.82 eV), and the photo-responsivity to red light up to 0.66 mA/W. The photo-responsivity of the films enhances for 150 keV Fe, 60 keV Au, 80 MeV Si and 100 MeV Ni ions and reduces for 100 and 200 keV Al and Cu and 100 MeV Ag ions. These changes are strongly correlated with the electronic energy loss of the ions in the films. The study demonstrates the applicability of low and high energy ions to improve the photo-response and also reveals the possibility to estimate the extent of its progress in ZTP and other light-sensing materials relevant for photo-detector and solar cell applications.