Abstract
ZnGa2O4 is a promising semiconductor for developing high-performance deep-ultraviolet photodetectors owing to a number of advantageous fundamental characteristics. However, Zn volatilization during the ZnGa2O4 growth is a widely recognized problem that seriously degrades the film quality and the device performance. In this study, we report the synthesis of epitaxial ZnGa2O4 thin films by pulsed laser deposition using a non-stoichiometric Zn1+xGa2O4 target. It is found that supplementing excessive Zn concentration from the target is highly effective to stabilize stochiometric ZnGa2O4 thin films during the PLD growth. The influence of various growth parameters on the phase formation, crystallinity and surface morphology is systematically investigated. The film growth behavior further impacts the resulting optical absorption and thermal conductivity. The optimized epitaxial ZnGa2O4 film exhibits a full width at half maximum value of 0.6 degree for a 120 nm thickness, a surface roughness of 0.223 nm, a band gap of 4.79 eV and a room-temperature thermal conductivity of 40.137 W/(m⋅K). This study provides insights into synthesizing epitaxial ZnGa2O4 films for high performance optoelectronic devices.
Highlights
Deep-ultraviolet photodetectors (DUV PDs) with the characteristic spectral response in the range of 200–280 nm [1] have attracted significant research interests owing to their broad applications including optical communication, missile detection, environmental monitoring, and biochemical analysis [2,3,4,5,6]
We report the growth of epitaxial ZnGa2O4 films by pulsed laser deposition wit non-stoichiometric Zn1+xGa2O4 (x = 6.5) target
We report the growth of epitaxial ZnGa2O4 films by pulsed laser deposition with a non-stoichiometric Zn1+xGa2O4 (x = 6.5) target
Summary
Deep-ultraviolet photodetectors (DUV PDs) with the characteristic spectral response in the range of 200–280 nm [1] have attracted significant research interests owing to their broad applications including optical communication, missile detection, environmental monitoring, and biochemical analysis [2,3,4,5,6]. Development of advanced DUV PD techniques applies strict requirements on the device responsivity, the response time, device weight and reliability. This becomes challenging for conventional DUV PDs including silicon-based PDs and photomultiplier tubes, which require to integrate additional UV filters and are more vulnerable to thermal and radiation damage [7]. A well-recognized challenging issue is the impurity phase segregation due to the stoichiometry modification or metastable phase formation [2,18] Among these candidates, ZGO presents appealing advantages in fabricating highperformance DUV PDs, including the simple cubic structure, wide bandgap (4.6–5.2 eV). T. Thheesesveevreerevovloatlailtiizlaiztiaotnion oof fZZnnooccccuurrssdduurrininggtthheeZZnnGGaa22OO44fifilmlmggrorowwththdduueettootthheemmuucchhhhiigghheerr vvaappoorr pprreessssuurree ooff ZZnn tthhaann ththaat toof fGGaa. ZUnsi1n+xgGtah2eOn4otanr-gsteotic(xhi=om0)e,twrichiscinhgceo-ntasrigsetst of Gaap2pOr3oiamchp,uwreitysypstheamseatdicuaellytostZundyvothlaeteilfifzeacttisoonf (tFarigguetreZn1/b)G. aUrsaitniog, tghreownothn-tsetmoipcehriaotmureet,ric sionxgyeg-etnarpgreetsasuprperaonadchl,aswere flsuyesntecme oatnictahlelyphstausde ycotmhepoesffiteicotns, osuf rtfaarcgeemt Zonrp/Ghoalorgatyi,oo,pgtricoawl th tepmroppeerratiteusraen, doxtyhgeremn aplrceosnsduurectaivnidty.laser fluence on the phase composition, surface morphology, optical properties and thermal conductivity
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