Electrical Conduction Mechanisms in n-CdS/p-CuFeO₂ Heterojunction Diode

Abstract:

In this work, n-CdS/p-CuFeO₂ heterojunction diode was fabricated by thermal evaporating CdS thin films on 1 mm thick-CuFeO₂ ceramic substrate with substrate temperature kept at 373 K during evaporation process. The forward current-voltage characteristics of n-CdS/p-CuFeO₂ heterojunction in a temperature range of 100-300 K were investigated to determine the electrical parameters and conduction mechanism. It was found that, at forward bias below 0.5 V, the conduction mechanism of the diode is dominated by thermionic emission (TE) mechanism. At bias voltage above 0.5 V, the current transport is due to space charge limited current (SCLC) controlled by an exponential trap distribution in the band gap of CdS. The temperature dependence of the saturation current and ideality factor are well described by tunneling enhanced recombination at junction interface with activation and characteristic tunneling energy values as about 1.79 eV and E₀₀ = 86 meV, respectively. The value of interface state density (N_ss) evaluated from capacitance spectroscopy increases from 2.09x10¹¹ eV^-1cm^-2 (at 300 K) to 2.70x10¹¹ eV^-1cm^-2 (at 363 K). Free carrier concentration of 5.80x10¹³ cm^-3 at room temperature was estimated from capacitance-voltage measurements at 50 kHz.

• Periodical: Advanced Materials Research (Volumes 931-932)
• Pages: 122-126
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.931-932.122
• Online since: May 2014
• Authors: Thitinai Gaewdang*, Ngamnit Wongcharoen
• Keywords: I-V Characteristics, n-CdS/p-CuFeO₂ Heterojunction, Space Charge Limited Current, Thermionic Emission

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