Fabrication of p -Type Zns with Blue-Ag Emission by Triple-Codoping Method
- PDF / 76,049 Bytes
- 6 Pages / 596 x 842 pts (A4) Page_size
- 37 Downloads / 162 Views
FABRICATION OF p-TYPE ZnS WITH BLUE-Ag EMISSION BY TRIPLE-CODOPING METHOD S. Kishimoto1 , T. Yamamoto2 and S. Iida3 1)
Kochi National College of Technology, Monobe-otsu 200-1, Nankoku, Kochi 783-8508, Japan Department of Electronic and Photonic Systems Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-gun, Kochi 782-8502, Japan 3) Department of Electrical Engineering, Nagaoka University of Technology, Kamitomioka 1603-1, Nagaoka 940-2188, Japan 2)
ABSTRACT We have succeeded in the fabrication of low-resistivity p-type ZnS with blue -Ag emission by triple-codoping using Ag, a Zn-substituting species, In, a Zn-substituting species, and N, a S-substituting species. For the realization of blue-Ag emission at 436 nm, we use In species as co-activators with Ag activators. For the control of conduction type to obtain p-type ZnS thin films, we introduce N species as acceptors into ZnS codoped with the Ag and In. On the basis of the analysis of the experimental data and calculated results, we proposed a model for ZnS:(Ag, In, and N), in which some of the In species act as coactivators with Ag activators and other In species act as reactive codopants with N acceptors.
INTRODUCTION ZnS with a direct bandgap of 3.68 eV at room temperature has attracted attention because of their possible application in highly efficient short-wavelength light-emitting devices (LED) and blue injection-laser diodes (LD). Ag impurities, which are Zn-substituting species, are well known to be the blue-Ag center (usually called ‘activator’)[1,2]. In order to realize the blue emission of approximately 440 nm (2.81 eV), it is necessary to introduce donors as ‘coactivators ’ into ZnS films. On the other hand, we must solve a crucial doping problem: ZnS has proven to be difficult to be doped as p-type while it is very easy to obtain n-type doped ZnS. Very recently, p-type ZnS doped with N species (ZnS:N) was fabricated by Svob et al. [3] In order to solve the doping problem described above for wide-band-gap semiconductors such as GaN and ZnO, we have proposed a codoping method using acceptors and reactive donors. The theoretical predictions for the realization of p-type ZnO by codoping of Ga or Al donors with N acceptors (ZnO:(N, Ga or Al)) and of p-type GaN:(Mg, Si or O) were proposed by us [4,5]. Subsequent confirmation of the applicability of the codoping to fabricate low-resistivity p-type ZnO [6] and GaN [7] was sought by some experimental groups. We have succeeded in the realization of low-resistivity p-type ZnS with blue-Ag emission [8-11]. Then, the aim of this paper is to give how to fabricate the material described above. For ZnS with zinc-blende structure, which is favored by covalent compounds, the codoping method using the overlap between donor orbitals with a large Bohr radius and N-acceptor ones is very effective for good p-type conductive to occur, as will be demonstrated below.
F3.1.1 Downloaded from https://www.cambridge.org/core. University of Cambridge, on 04 Feb 2020 at 12:07:32, subject to the Ca
Data Loading...
