Low residual doping level in homoepitaxially grown ZnO layers

Abstract

Residual and intentional n-type doping of ZnO thin films grown by metal-organic vapor phase epitaxy on sapphire and ZnO substrates

Decay kinetics of the defect-based visible luminescence in ZnO

“…Therefore, two channels of observed exciton luminescence quenching can be related to thermal disintegration of both donor-bound and free exciton, in agreement with other recent reports [7,8]. To interpret the physical mechanism of quenching processes of visible emission appears more difficult, since the nature of related defect centers is not entirely clear.…”

Compared optical properties of ZnO heteroepitaxial, homoepitaxial 2D layers and nanowires

“…This behavior was also reported in Ref. [2] for MOVPE homoepitaxially grown samples. It was found the FX to D1X intensity increases when increasing the VI/II flux ratio.…”

“…For a VI/II flux ratio of 25,000, the D1X emission intensity is similar to the one of the FX emission. In addition, for this MOVPE sample, only one activation energy of 60 meV, corresponding to the FX binding energy is measured in temperature-dependent PL measurements [2]. So it seems that increasing the VI/II ratio allows one to reduce the unintentional doping level.…”

“…The main difference between these samples is represented by their substrates: the first sample was homoepitaxially grown on a ZnO hydrothermal substrate, the second one was grown on c-sapphire substrate and the third on an MgO buffer layer. Second, the optical properties of the homoepitaxial MBE layer is compared to those of 2D homoepitaxial layers grown by metal organic vapour-phase epitaxy (MOVPE) [2]. Finally, as 1D ZnO structures such as nanowires (NWs) are expected to have a high crystalline quality and to be compatible with a large range of substrates, the optical properties of ZnO NWs grown on p-type GaN and sapphire are also investigated and compared to those of the MBE-grown 2D layers.…”

Shallow Donors and Compensation in Homoepitaxial ZnO Thin Films

“…[1][2][3][4][5][6][7][8][9][10][11] Mostly the structural and morphological properties have been discussed. Although the quality of ZnO substrates still needs to be improved, in most cases considerably improved properties of homoepitaxial ZnO thin films compared to heteroepitaxial ZnO layers (mostly on sapphire and SCAM substrates) are found.…”