Epitaxial growth of nonpolar m-plane ZnO epilayers and ZnO/Zn_0.55Mg_0.45O multiple quantum wells on a LiGaO₂ (100) substrate

Abstract

Nonpolar m-plane ZnO epilayers and ZnO/Zn0.55Mg0.45O multiple quantum wells were grown on a LiGaO2 (100) substrate by molecular beam epitaxy.

Anisotropic photoluminescence of nonpolar ZnO epilayers and ZnO/Zn1-xMgxO multiple quantum wells grown on LiGaO2 substrate

“…Figure 3(a) shows the 90°polarized PL spectra of the m-plane ZnO epilayer at 10-300 K. A moderate emission at 3.260 eV and a strong emission at 3.221 eV with a full width at half maximum (FWHM) of 25 meV are observed at 10 K. The former corresponds to the near band edge (NBE) exciton emission (superposition of donor bound exciton D 0 X and free exciton FX) [26,27], whereas the latter is a BSF related emission [20,28]. The strong BSFs related peak is the result of the high density of BSFs of 1×10 6 cm −1 in the epilayer reported previously [22]. As suggested, the BSFs are treated as quantum wells of a type-II band alignment [29,30].…”

“…The surface morphology, microstructure and strain relaxation conditions were characterized in our previous work [22]. Here we focus on the polarized light emission.…”

“…LiGaO 2 (LGO) (100) and ( 010) substrates have been demonstrated to be suitable for growing nonpolar m-and a-plane ZnO epilayers, respectively [22][23][24]. The lattice mismatch is 1.9% in [1120] LGO, all of which will further decrease at the actual growth temperature of 700°C due to thermal expansion.…”

Elastic and inelastic strain in submicron-thick ZnO epilayers grown on r-sapphire substrates by metal–organic vapour phase deposition

“…Among the many factors affecting the properties of a thin film, strain is one of the most important. At the interfacial surface, defects and threading dislocations appear and can propagate through the epilayer (Ashrafi et al, 2004;Yan et al, 2015). These problems can influence electronic and optical properties, affecting both the device lifetime and operating wavelength (Abadias et al, 2018;Hoat et al, 2019).…”

“…1 12Þ] orientations exhibit built-in electric fields that worsen the electronic properties (Yan et al, 2015). The undesirable spontaneous and piezoelectric polarization that appears in the active zone mainly affects the quantum efficiency of the devices based on these layers.…”