MgxZn1-xO合金制备及MgZnO/ZnO异质结构的光学性质

利用射频等离子体辅助的分子束外延(P-MBE)技术在c面的蓝宝石衬底上生长了具有不同Mg含量(0≤x≤0.28)的六方相MgZnO合金薄膜,研究了该系列样品Raman频移的幅度与合金组分的对应关系,为MgZnO合金中Mg含量的确定提供了新的方法。在此基础上选择具有合适带宽的MgZnO合金作为垒层,制备了MgZnO/ZnO量子阱结构。在较高的光激发密度下,观测到了发光强度随激发密度的超线性增加,并将之归因于激子-激子碰撞引起的超辐射过程。

MgxZn1-xO Alloy Grown by P-MBE and Optical Properties of MgZnO/ZnO Heterostructure

Hexagonal Mg_xZn_1-x Oalloy layers with 0≤x<0.3 have been grown by plasma-assisted molecular beam epitaxy on sapphire (006) substrates. Their crystal structures are characterized by X-ray diffraction spectroscopy. The resonant Raman spectra were measured using 325 nm line from He-Cd laser by backscatte-ring geometry. The long wavelength frequencies of ZnO-like optical phonons measured in the resonant Raman spectra can be expressed as linear functions of x:ω(LO)=(580+147x)cm^-1.ZnO/Mg_0.12Zn_0.88 Osingle quantum well (SQW) with 1.5 nm ZnO well width was grown on sapphire substrate. In the PLspectra at 5 K, Pband located at 3.371 eV was observed. At excitation densities higher than 76 kW/cm², the Pband shows a typical super linear increase characteristic. With increasing the excitation density further, the Pband converges gradually at the saturation value of 3.354 eV with significant narrowing. It was attributed to the gradually enhanced exciton-exciton scattering. The integrated emission intensity versus excitation density follows the relation of I_ex^3.13. This superlinear increase indicates the typical properties of a super-radiation recombination.