Photoluminescence and built-in electric field in ZnO∕Mg0.1Zn0.9O quantum wells

Abstract

Photoluminescence study of ZnO∕Mg0.1Zn0.9O quantum wells with graded well width (Lw) was carried out at 4.2K. The emission evolution from quantum confinement regime to quantum-confined Stark regime was observed clearly. For large Lw, the emission splits into two peaks which are attributed to the emissions of ZnO band edge and separately localized carriers, respectively. The internal electric field in the well layer was estimated to be ∼0.3MV∕cm, being similar to previous reports. The results are useful in designing ZnO QW based optoelectronic devices.

Ultrafast spectroscopy of ZnO/ZnMgO quantum wells

“…The magnitude of the internal electric field is highly dependent on the Mg concentration, and for ZnO/Zn 1−x Mg x O QWs has been extrapolated to be 4.1x (in MV/cm) . Other measurements for QWs with different Mg concentration in the barriers agree with this value, within experimental uncertainties [29,32,33].…”

Characterization of microstructure and defects in epitaxial ZnO films on Al2O3 substrates by transmission electron microscopy

“…In this case, a strong built-in electrostatic field appears in the ZnO film as a result of spontaneous and piezoelectric polarizations caused by the noncentrosymmetric nature of wurtzite crystal structure. The polarization-induced electric field results in the quantum confined Stark effect (QCSE) [2,3], which acts as a negative factor on a performance of the light-emitting devices [4][5][6]. One of the direct ways to eliminate the effect of polarization fields on devices is growing the films with nonpolar directions.…”

Effect of growth parameters on MgxZn1−xO films grown by metalorganic chemical vapour deposition

“…The shift of the PL peaks thus indicates an increase in bandgap energy due to an increase in Mg content in the different films. The broadening of the peaks results from alloying, inhomogeneous strain, dislocations and finite domain size [3], leading to statistical potential fluctuations. The alloy disorder in Mg x Zn 1 À x O is for the most part due to the large bandgap difference between ZnO and MgO.…”

“…Although optical properties of ZnO and MgO have been well established, properties of their ternary alloy Mg x Zn 1 À x O still require more in-depth investigation. Successful attempts to grow Mg x Zn 1 À x O using MOCVD have been reported [1,2], yet a better understanding of Mg incorporation needs to be achieved in order to realize good quantum wells [3] and other heterostructures.…”