Pure and Mg doped ZnO thin films were deposited at 400 °C on glass substrates by pulsed laser deposition. An x-ray diffractometer (XRD) was used to investigate the structural properties of the thin films. It is found that all the thin films have a preferred (002) orientation. The peak position of (002) orientation is found to shift from 34.39° to 34.55°. The lattice constants of ZnO thin films were also obtained from XRD data. It is found that, with the increase of the dopant concentration, the lattice constant a decreases from 3.25 to 3.23 Å, and c decreases from 5.20 to 5.16 Å. From the spectrophotometer transmittance data, the band gap energies of the thin films were calculated by a linear fitting process. The band gap energy of Mg doped ZnO thin film increases with increasing dopant concentration. In photoluminescence (PL) spectra, two PL emission peaks are found in pure ZnO thin films, one is the near band edge (NBE) emission at 3.28 eV, and the other is green-yellow-red emission at around 2.4 eV. However, with the increase of the dopants, no green-yellow-red emissions are found in PL of Mg doped ZnO thin films. The NBE emission has a blueshift compared with that of pure ZnO thin film (as much as 0.12 eV). As time goes on, NBE emission in pure ZnO thin film is enhanced, and the green-yellow-red emissions disappear.

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Many fault-tolerant and intrusion-tolerant systems require the ability to execute unsafe programs in a realistic environment without leaving permanent damages. Virtual machine technology meets this requirement perfectly because it provides an execution environment that is both realistic and isolated. In this paper, we introduce an OS level virtual machine architecture for Windows applications called Feather-weight Virtual Machine (FVM), under which virtual machines share as many resources of the host machine as possible while still isolated from one another and from the host machine. The key technique behind FVM is namespace virtualization, which isolates virtual machines by renaming resources at the OS system call interface. Through a copy-on-write scheme, FVM allows multiple virtual machines to physically share resources but logically isolate their resources from each other. A main technical challenge in FVM is how to achieve strong isolation among different virtual machines and the host machine, due to numerous namespaces and interprocess communication mechanisms on Windows. Experimental results demonstrate that FVM is more flexible and scalable, requires less system resource, incurs lower start-up and run-time performance overhead than existing hardware-level virtual machine technologies, and thus makes a compelling building block for security and fault-tolerant applications.

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