Transition from n- to p-Type of Spray Pyrolysis Deposited Cu Doped ZnO Thin Films for NO₂ Sensing

Fabrication and characterization of Pd/Cu doped ZnO/Si and Ni/Cu doped ZnO/Si Schottky diodes

“…They performed photoluminescence experiments and observed that shallow acceptor state at 0.15 eV above the valence band edge. Rahmani et al [14] deposited Cu doped ZnO thin films on the glass substrate using spray pyrolysis coating system. They suggested that p-type conductivity is due to the holes generated by the incorporation of Cu atoms on Zn sites.…”

p-Type behaviour of electrodeposited ZnO:Cu films

“…Thus, group IB elements have been proposed as the best possible candidates for p-type ZnO doping [5]. Theoretical studies predict that Cu-doped ZnO can exhibit p-type behaviour [6], and both p-and n-type behaviours have been reported for Cu-doped ZnO using vacuum deposition methods [7][8][9].…”

Nanocrystalline Thin Film Gas Sensors

“…It has been experimentally seen that for ordinary thick film microcrystalline sensors the operating temperature may be as high as 350°C but for nanocrystalline materials it can be lowered down to *200°C [15][16][17][18]. Also notable is the fact that the material shows a much greater response at the same temperature compared to a microcrystalline thin film.…”

“…Zinc oxide is one such material which has become a well-established sensor material owing to its easy synthesis procedure, good electrical properties and in particular its compatibility with Si leading to MEMS-based chemical sensors [14]. Many reports regarding the sensing of various gases and gas mixtures like H 2 [15,16], CO [17], NO 2 [18], ozone [15], acetone vapor [19], ethanol vapor [20], LPG [21,22] using ZnO nanostructures have been published recently. Due to its high surface to volume ratio the gas sensing properties of aligned ZnO nanorods are markedly better compared to their conventional thin film counterparts and they have the advantages of greater sensitivity, faster response, and lower operating temperatures (which is essentially useful in lowering the power requirements for possible integration with CMOS technology).…”