Annealing effects on metal-ZnO interface for improvement performance of Thin-film Transistors
- PDF / 28,264,878 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 103 Downloads / 196 Views
Annealing effects on metal-ZnO interface for improvement performance of Thin-film Transistors Miguel A. Dominguez*1, Francisco Flores1, Adan Luna1, Salvador Alcantara1, Javier Martinez1, Jose A. Luna-Lopez1, Pedro Rosales2 and Claudia Reyes2. 1 Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP), Puebla, 72570, Mexico. 2 National Institute for Astrophysics, Optics and Electronics (INAOE), Electronics Department, Luis Enrique Erro No. 1, Puebla, Z.P. 72840, Mexico. E-mail: [email protected]. ABSTRACT In this work, the annealing effects at 180°C in Aluminum-ZnO contacts as function of time were studied. Also, the application in TFTs of ZnO films obtained at low-temperature (200°C) are presented. The ZnO films obtained by ultrasonic Spray Pyrolysis at 200 °C were deposited over Aluminum contacts on SiO2/Si wafers to demonstrate the use of active layer in thin-film transistors. The results show that an improvement can be obtained in metal-ZnO interfaces by low-temperature annealing treatments. However, long annealing time degrade the metal-ZnO interface and may affect the electrical performance of the device. INTRODUCTION Currently, Zinc Oxide films can be obtained by several techniques, where spray pyrolysis offers low-cost, simplicity, is useful for large area applications and no need of high vacuum. These advantages make of great potential the use of ZnO by spray pyrolysis as active layer of low-cost thin-film transistors (TFTs) applications. Low-cost TFTs applications are possible by the use of low-cost plastic substrates. Although, ZnO TFTs fabricated by spray pyrolysis have already been demonstrated [1-5], the temperature of deposition to obtain high performance devices is still high enough to be compatible with low-cost electronics. In these devices is desirable to have a low contact resistance for an optimum electrical performance. In an ideal metal-semiconductor contact, there are no barriers to the carrier flow in either the positive or the negative direction. Ideally, this occurs when there are no interface states and, the metal and the semiconductor work functions are about the same. However, usually, these are nearly impossible [6]. Some authors have reported the reduction of the contact resistance in metal-ZnO interfaces [7-15]. However, it is well-known, that ZnO films are highly dependent on the deposition technique and deposition conditions, resulting in different surface conditions and defects density distribution. For this reason, a quantitative comparison of the contact resistance would not be feasible, because it depends on the quality of the ZnO film and metal contact used. Typically, to improve the properties of the as-deposited ZnO films, annealing treatment after deposition of the film has been reported previously [16-19]. However, some authors reported that high annealing temperatures degraded the metal-ZnO contact increasing the contact resistance [7, 8, 15]. Moreover, annealing treatments in order to improve t
