A growth of A–Z phthalocyanine layers onto Si by thermal evaporation process to achieve organic heterojunction diodes

Abstract

Thermally evaporated organic heterojunction (OHJ) diodes based on A–Z phthalocyanine (ZnPc/pSi and AlPc/Si) are investigated. Here, we study the electronic parameters of ZnPc/pSi and AlPc/Si organic heterojunction diodes. Such organic heterojunctions are produced by thermal evaporation process in vacuum at very low pressure. For this purpose, the current–voltage (I–V) characteristics at room temperature under dark conditions for the organic aluminum and zinc (A–Z) phthalocyanine materials are measured. Firstly, the electronic parameters of the organic heterojunctions including ideality factor n, barrier height (Φb), series resistance (RS) are extracted via Cheung and Norde methods respectively. A high rectification ratio (RR) in order of 2 × 104 is recorded for ZnPc/p-Si contacts. Non-ideal behavior of AZPc OHJ is revealed n ∼ 2.4, series resistance and barrier height are of 2 kΩ and 0.4 eV. Secondly, the conduction mechanism of both AlPc/Si and ZnPc/Si contacts are investigated. SCLC is the dominated conduction mechanism throughout the OHJ device.