p-type in ZnO:N by codoping with Cr
- PDF / 145,666 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 37 Downloads / 195 Views
E6.1.1
p-type in ZnO:N by codoping with Cr E. Kaminska1, A. Piotrowska1, J. Kossut2, R. Butkute3, W. Dobrowolski3, K. Golaszewska1, A. Barcz1,3, R. Jakiela3, E. Dynowska3, E. Przezdziecka2, D. Wawer1 1
Institute of Electron Technology, al. Lotnikow 32/46, 02-668 Warszawa, Poland Institute of Physics, Polish Academy of Sciences, and ERATO Semiconductor Spintronics Project, al. Lotnikow 32/46, 02-668 Warszawa, Poland 3 Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warszawa, Poland 2
ABSTRACT We report on the fabrication of p-ZnO films by thermal oxidation of Zn3N2 deposited by reactive rf sputtering. With additional chromium doping we achieved p-type conductivity with the hole concentration ~5x1017cm-3 and the mobility of 23.6 cm2/Vs at room temperature. We developed a method of surface passivation of p-ZnO that maintains its p-type conductivity over time-scale of months. INTRODUCTION There is a growing interest in the use of transparent-oxide electronics for optoelectronic circuits due to their high-temperature performance and radiation hardness. Transport properties of transparent oxides can be controlled across a very wide range such that they can behave either as insulators, n-type semiconductors or metals. Recent several breakthroughs in the growth of ptype ZnO have inspired researchers to optimise p-type doping approaches and procedures of this material, however, the fabrication of p-type material which would satisfy device requirements remains a formidable technological challenge. Various deposition techniques, including chemical vapour deposition [1], molecular beam epitaxy [2], pulsed laser ablation [3], sputter deposition [4], or oxidation of zinc nitride [5] have been employed for the growth of p-type ZnO. Acceptor doping was achieved with nitrogen originating (from various sources: NH3, NO, NH4NO3, N2, N2O) or with arsenic or phosphorous. To enhance the incorporation of acceptors, a codoping method employing reactive codopants such as Al, Ga or In has been proposed [6] and successfully implemented [7]. In this paper we report on the fabrication of ZnO with p-type conductivity via thermal oxidation of Zn3N2. This concept is similar to the one published by Li et al. [5]. In contrast to their method with zinc nitride grown by plasma enhanced chemical vapour deposition, our starting material was deposited by reactive sputtering from metallic Zn in N2-Ar plasma. Introducing chromium as a codopant during the fabrication of Zn3N2, we achieved p-type ZnO:N:Cr with superior electrical properties. EXPERIMENTAL PROCEDURE Thin ZnO films were prepared either on quartz, or sapphire or on a 3 µm thick (001) oriented undoped GaN films on sapphire. GaN substrates have been used with an intention to facilitate the growth of hexagonal ZnO. Prior to deposition, the substrates were degreased in hot organic
E6.1.2
solvents and in-situ sputter etched in Ar+. Sputter depositions were performed in a three-target magnetron sputtering system, in RF mode using Zn (99,995%) target and a mixture of
Data Loading...
