Temperature-dependent photoluminescence of ZnO films codoped with tellurium and nitrogen

Abstract

The photoluminescence spectra as well as their temperature dependence of the tellurium and nitrogen (Te-N) codoped ZnO films have been investigated in detail. Explicit evidences of the emissions related to two acceptors [A1: the NO-Zn-Te subunits and A2: the conventional N ions substituting on oxygen sites (NO)] have been found. The acceptor activation energy level of the A1 (∼118–124 meV) is much shallower than that of the A2 (∼224–225 meV) indicating that the A1 should be mainly responsible for the room-temperature p-type nature of the codoped samples. Meanwhile, the acceptor activation energy level of A1 shows a slight decrease (∼6 meV) as the Te atomic concentration increases in the codoped samples implying that the actual form of the A1 may be a mixture of the NO-Zn-nTe (n = 1, 2, 3, 4). More incorporation of the Te ions into N-doped ZnO films not only makes the acceptor energy level shallower but also improves the crystalline quality and results in the efficiently suppressed native donorlike defects. The optical properties accord well with the crystalline and electrical ones indicating that the Te-N codoping technique is a potentially feasible route to get controllable p-type ZnO materials.

Zinc vacancy related emission in homoepitaxial N-doped ZnO microrods

“…we can get α¼5.7 Â 10 À 4 eV/K and β¼793 K, which are close to the values in literature [26,43]. As clearly shown in Fig.…”

“…Using the values measured at 9 K, the E A is calculated to be $ 126 meV, related to a shallow acceptor state associated with the A 0 X (3.359 eV) and DAP (3.240 eV) emission. Haynes [49] reported that the E loc of the acceptor is proportional to the E A , and the ratio is 0.14 according to our experiment data, in the range of 0.07-0.24 reported before [26,50]. At last, we assign the emission at 3.318 eV to the BX because its intensity decreases with increasing temperature and disappears around 60 K. It is unlikely that D 0 X appears in this energy range, and we ascribe this emission to another A 0 X with E loc ¼ 59 meV, corresponding to a deep acceptor state.…”

“…Among the various acceptor dopants, N is widely considered as the best candidate for p-type doping in ZnO since it has a similar atomic radius and electronegativity with O [22]. To date, many tangible evidences of N-doped p-type ZnO materials have been reported [23][24][25][26][27], although a theoretical calculation inclined that O-site N (N O ) was actually a deep acceptor with exceedingly high ionization energy of 1.3 eV [28]. A few studies also reported the donoracceptor pair (DAP) recombination with the zero-phonon-line (ZPL) position in the range of 3.21-3.24 eV in N-doped ZnO materials [23,[29][30][31][32][33], and the chemical origin of the acceptor remains controversial.…”

Effects of indium doping on the crystallographic, morphological, electrical, and optical properties of highly crystalline ZnO films

“…The system has been used to dope various elements into ZnO films, e.g., gallium [8], nitrogen [9], tellurium [10], manganese [11], and magnesium [12]. The configurations of the system can be thus referenced elsewhere.…”

ZnO Doping and Defect Engineering—A Review

“…The codoping experiments show that Te can be helpful in producing intrinsic ZnO thin films [151]. An increased concentration of Te ions into N-doped ZnO films not only made the acceptor energy level shallower but also resulted in improved crystalline quality and efficient suppression of native donor-like defects [152]. Zr-N codoping method was proved to successfully produce p-type ZnO with excellent electrical properties.…”