The Role of Work Function and Band Gap in Resistive Switching Behaviour of ZnTe Thin Films

Abstract

Resistive switching behavior by engineering the electrode work function and band gap of ZnTe thin films is demonstrated. The device structures Au/ZnTe/Au, Au/ZnTe/Ag, Al/ZnTe/Ag and Pt/ZnTe/Ag were fabricated. ZnTe was deposited by thermal evaporation and the stoichiometry and band gap were controlled by varying the source–substrate distance. Band gap could be varied between 1.0 eV to approximately 4.0 eV with the larger band gap being attributed to the partial oxidation of ZnTe. The transport characteristics reveal that the low-resistance state is ohmic in nature which makes a transition to Poole–Frenkel defect-mediated conductivity in the high-resistance states. The highest Roff-to-Ron ratio achieved is 109. Interestingly, depending on stoichiometry, both unipolar and bipolar switching can be realized.