Annealing temperature effect on structural, electronic features and current transport process of Au/CoPc/undoped-InP MPS-type Schottky structure

Abstract

The influence of annealing on structural, electronic features and the current transport process of the Au/CoPc/undoped-InP (MPS)-type structure is explored. Raman measurements of as-deposited CoPc thin films reveal significant vibrational bands at 593 cm−1, 682 cm−1 and 1537 cm−1 assigned to C-C and C-N band stretching, showing the structural confirmation of CoPc films. The surface topology of CoPc is assessed by AFM at various annealing temperatures. The roughness of CoPc films falls with rising annealing temperature up to 200 °C and then slightly rises after annealing at 300 °C and 400 °C. The electrical features of the MPS structure are explored by the I-V method and observed good rectification nature regardless of annealing temperatures. The mean barrier heights are estimated to be 0.76 eV, 0.89 eV, 0.91 eV, 0.86 eV and 0.85 eV for as-deposited, 100 °C, 200 °C, 300 °C and 400 °C by statistical distribution analysis. Results showed that the BHs increase as annealing rises to 200 °C and decrease after annealing at 300 °C and 400 °C. The derived series resistance of the MPS structure reduces with rising annealing up to 200 °C and then rises after annealing at 300 °C and 400 °C. The acquired density of states (NSS) of the MPS structure varied with annealing temperature may be the reduction in the recombination center and the prevalence of an interfacial layer between the CoPc and InP layers. Findings suggest that the PFE governs reverse current in the lower bias region, while, the SE ruled reverse current in the higher bias region of the MPS structure irrespective of annealing temperatures.