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Unipolar transparent vertical diode based on ZnMgO/ZnO heterostructure films

Jong-Gul Yoon ,  Sung-Woo Cho 

University of Suwon, Suwon 445-743, Korea, South


Recently, oxide semiconductor materials have attracted much attention for their potential application in optoelectronic devices and transparent electronics. ZnO is one of the promising material because of its direct band gap (~ 3.3 eV) and large exciton binding energy (~60 meV). Although there have been many reports demonstrating ZnO based devices such as p-n junction ultraviolet-blue light emitting diodes and UV photodetectors, ZnO-based transparent thin film diodes has been less studied probably due to the difficulties in achieving p-type ZnO film.  Here, we report on the fabrication of a unipolar transparent thin film diode based on ZnO through a heterojunction implementation, without invoking to p-type materials.

Since unipolar diodes, which are one of majority carrier devices,  have a high switching speed, unipolar transparent thin film diodes can have many device applications in transparent electronics and nonvolatile resistive random access memories.   Our ZnO-based unipolar vertical diodes utilize a heterostructure of ZnO and Zn1-xMgxO (ZnMgO) film of graded-composition. ZnO and ZnMgO heterostructure films were deposited on indium-tin-oxide coated glass substrate by using ultrasonic spray pyrolysis. The diodes showed excellent rectifying characteristics with the rectification ratio exeeding 103 in the range of applied volages between -3.0 and +3.0 V and turn-on voltage about 0.8-1.0 V.  Potential barriers produced in the diode structures and controllability of the diode characteristics will be discussed in terms of the graded band gap of ZnMgO films.


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Presentation: Oral at E-MRS Fall Meeting 2009, Symposium C, by Jong-Gul Yoon
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-11 07:51
Revised:   2009-07-08 07:57