Controlled growth and properties of p-type cuprous oxide films by plasma-enhanced atomic layer deposition at low temperature

Abstract Various copper oxide films were successfully grown by plasma-enhanced atomic layer deposition (PEALD) at a low temperature of 100 °C. X-ray diffraction analysis of the films indicated that phase-controlled deposition of CuO x phases (0 ≤  x x ( x  = 0.9) film with a smooth surface (RMS roughness of 0.97 nm) was obtained. On the other hand, when the number of Cu deposition steps was increased to three, a CuO x ( x  = 0.6) thin film with a polycrystalline phase (grain size: 25 nm) was obtained. The as-deposited CuO 0.6 film showed p-type conductivity (Hall mobility ∼37 cm 2 /V·s and hole concentration ∼5.4 × 10 14  cm −3 ). Moreover, p-type CuO 0.6 /n-type ZnO heterojunction diodes fabricated on a flexible polyethylene terephthalate substrate exhibited electrical rectification with a threshold voltage of 1.2 V.