Structural and optical properties of ZnCdO/ZnO multiple quantum wells grown on sapphire substrates using pulsed laser deposition

Abstract

High quality Zn0.92Cd0.08O/ZnO multiple quantum wells with smooth interfaces have been prepared on c-plane sapphire substrates by pulsed laser deposition. The periodic structure has been characterized by scanning transmission electron microscope and energy dispersive x-ray spectroscopy line scans. The temperature dependent photoluminescence of Zn0.92Cd0.08O/ZnO exhibits an inconspicuous S-shaped property due to a combined effect of the slightly disordered ZnCdO alloy. We can observe both quantum confinement effects and quantum-confinement Stark effect in the quantum wells. We can modulate the well emission energy from 2.90 to 3.085 eV by varying the well thickness at room temperature.

VIS-UV ZnCdO/ZnO multiple quantum well nanowires and the quantification of Cd diffusion

“…These results could point to the presence of quantum confinement in the thinner wells (L w < r B ). Indeed, other groups have interpreted similar results in heterostructures with lower nominal Cd contents in terms of quantum confinement [6][7][8][9][10]. Nevertheless, diffusion effects can significantly alter the heterostructure and an accurate interpretation requires a detailed analysis of the sample microstructure.…”

“…These problems were already likely inherent to the first reports on ZnCdO/ZnO heterostructures by Sadofev et al [5,6], where the maximum nominal Cd content in the quantum well was around 12-17%. Later work by other groups have reported heterostructures with nominal Cd contents from 8% [7,8], through 15% [9], and up to 25% [10]. This implies that the photoluminescence (PL) wavelength region covered so far does not reach energies below ∼2.5 eV (determined at low temperature).…”

Polarization-induced ultrahigh Rashba spin-orbit interaction in ZnO/CdO quantum well

“…Defect control in ZnO is also difficult in the fabrication of ZnO/CdO QWs. High quality ZnO quantum well can be achieved by ozone-assisted molecular beam epitaxy and pulsed laser deposition [32,40], and high quality ZnO/CdO QWs can be synthesized by nonequilibrium laser plasma ablation when a very thin CdO is deposited on ZnO interlayers to sustain its wurtzite phase [41] Here, we demonstrate the RSOI modulated by the stress-induced polarization field of ZnO/CdO QWs. The QW is selected as our studying target because polarization field can drive a topological phase transition with a stress-dependent band inversion [42].…”

Fabricating functionally graded films with designed gradient profiles using pulsed laser deposition

“…Among many deposition techniques, pulsed laser deposition (PLD) is regarded as one of the most capable physical vapor deposition methods because materials with complex stoichiometry can be ablated and deposited by using a high intensity laser. [1][2][3][4][5] One important research topic in pulsed laser deposition is the fabrication and use of functionally graded films. This is a popular technique to fabricate a film with advanced and/or improved functionality by designing a film with more than one material.…”