This article describes the historical context, technical challenges, and main implementation techniques used by VMware Workstation to bring virtualization to the x86 architecture in 1999. Although virtual machine monitors (VMMs) had been around for decades, they were traditionally designed as part of monolithic, single-vendor architectures with explicit support for virtualization. In contrast, the x86 architecture lacked virtualization support, and the industry around it had disaggregated into an ecosystem, with different vendors controlling the computers, CPUs, peripherals, operating systems, and applications, none of them asking for virtualization. We chose to build our solution independently of these vendors.As a result, VMware Workstation had to deal with new challenges associated with (i) the lack of virtualization support in the x86 architecture, (ii) the daunting complexity of the architecture itself, (iii) the need to support a broad combination of peripherals, and (iv) the need to offer a simple user experience within existing environments. These new challenges led us to a novel combination of well-known virtualization techniques, techniques from other domains, and new techniques.VMware Workstation combined a hosted architecture with a VMM. The hosted architecture enabled a simple user experience and offered broad hardware compatibility. Rather than exposing I/O diversity to the virtual machines, VMware Workstation also relied on software emulation of I/O devices. The VMM combined a trap-and-emulate direct execution engine with a system-level dynamic binary translator to efficiently virtualize the x86 architecture and support most commodity operating systems. By relying on x86 hardware segmentation as a protection mechanism, the binary translator could execute translated code at near hardware speeds. The binary translator also relied on partial evaluation and adaptive retranslation to reduce the overall overheads of virtualization.Written with the benefit of hindsight, this article shares the key lessons we learned from building the original system and from its later evolution.

In20~-Si, In203-Ge, Ir~203-GaAs, and I,n203-InP heterojunction solar cells have been fabricated and their photovoltaic properties have been investigated. All devices show rectifying and photovoltaic effects. The experimental results can be explained by a simple heterojunction energy band diagram. In order to match the experimentally observed polarities of the open-circuit voltage and short-circuit current of these heterojunction solar cells, the electron affinity of In203 materials is determined to be 4.45 eV. The substrateresistivity dependence of open-circuit voltage is consistent with the energy band diagram using the electron affinity value of 4.45 eV for In203. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.214.17.222 Downloaded on 2015-03-13 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.214.17.222 Downloaded on 2015-03-13 to IP

GaAs metal-insulator-semiconductor solar cells with a physically deposited Bi2O3 interfacial layer have been investigated. The deposition techniques used in the study were electron beam and boat thermal evaporation. The cells fabricated with interfacial layers of Bi2O3 showed a substantial improvement in open-circuit voltage over cells made without the physically deposited oxide layer. An etch has been used which yields an irregular ’’textured’’ surface. Cells employing this surface had a higher short-circuit current than those made with smooth, polished surfaces. The open-circuit voltages of these textured cells were lower than those with smooth surfaces. Calculations of the dependence of open-circuit voltage on pinhole density are in agreement with these results since a rough surface has a greater probability of pinholes.

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Interfacial reactions at room temperature in multilayer thin film systems have been investigated by the Auger Electron Spectroscopy method. The multilayer thin film structure consists of metal, native oxide, and/or deposited interfacial layers on metal and semiconductor substrates. Various combinations of metals and interfacial layers on different substrates have been investigated. For the multilayer systems Au, Ag, Cu, and Cr were used as metals, GeO2, Bi2O3, SnO2, Sb2O3, Ga2O3, and As2O3 were used as interfacial layers, and GaAs, Si, and Fe were used as substrates. Only ’metal’ atoms from the interfacial oxide layers (Ge from GeO2, Sb from Sb2O3, Bi from Bi2O3, Sn from SnO2, and Ga and As from the native oxide mixture of Ga2O3 and As2O3) were detected on the metal surface of Metal-Interfacial layer-Semiconductor and Metal-Interfacial layer-Metal-Semiconductor structures. This indicates that the interfacial reaction takes place only at the metal-interfacial layer interface. ’Drive-out’ diffusion is present at all interfacial reactions. The interfacial reactions and the drive-out diffusion processes are thought to play an important role in the degradation of thin film multilayer structures.