Silicon-on-insulator (SOI) wafers are precisely engineered multilayer semiconductor/dielectric structures that provide new functionality for advanced Si devices. After more than three decades of materials research and device studies, SOI wafers have entered into the mainstream of semiconductor electronics. SOI technology offers significant advantages in design, fabrication, and performance of many semiconductor circuits. It also improves prospects for extending Si devices into the nanometer region (<10 nm channel length). In this article, we discuss methods of forming SOI wafers, their physical properties, and the latest improvements in controlling the structure parameters. We also describe devices that take advantage of SOI, and consider their electrical characteristics.

Frontiers of silicon-on-insulator

As discussed in the accompanying articles in this issue of MRS Bulletin, the optical properties of rare-earth (RE) elements have led to many important photonic applications, including solid-state lasers, components for telecommunications (optical-fiber amplifiers, fiber lasers), optical storage devices, and displays. In most of these applications, the host materials for the RE elements are various forms of oxide and nonoxide glasses. The emission can occur at visible or infrared (IR) wavelengths, depending on the electronic transitions of the selected RE element and the excitation mechanism. Until recently, the study of semiconductors doped with RE elements such as Pr and Er has concentrated primarily on the lowest excited state as an optically active transition. The presence of transitions at IR wavelengths (1.3 and 1.54 μm) that are coincident with minima in the optical dispersion and the loss of silica-based glass fibers utilized in telecommunications, combined with the prospect of integration with semiconductor device technology, has sparked considerable interest.The status and prospects of obtaining stimulated emission in Si:Er are reviewed by Gregorkiewicz and Langer in this issue and by Coffa et al. in a previous MRS Bulletin issue. While great progress is being made in enhancing the emission intensity of Er-doped Si, it still experiences significant loss in luminescence efficiency at room temperature, as compared with low temperatures. This thermal quenching was shown by Favennec et al. to de crease with the bandgap energy of the semiconductor. Hence wide-bandgap semiconductors (WBGSs) are attractive candidates for investigation as hosts for RE doping.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0883769400053045

Optoelectronic Properties and Applications of Rare-Earth-Doped GaN

Visible light emission has been obtained from Er-doped GaN thin films. The GaN was grown by molecular beam epitaxy on sapphire substrates using solid sources (for Ga, Al, and Er) and a plasma gas source for N2. Above GaN band-gap photoexcitation resulted in strong green emission. The emission spectrum consists of two narrow green lines at 537 and 558 nm and a broad peak at light blue wavelengths (480–510 nm). The narrow lines have been identified as Er transitions from the 2H11/2 and 4S3/2 levels to the 4I15/2 ground state. The intensity of the 558 nm emission decreases with increasing temperature, while the intensity of the 537 nm line actually peaks at ∼300 K. This effect is explained based on the thermalization of electrons between the two closely spaced energy levels.

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Visible emission from Er-doped GaN grown by solid source molecular beam epitaxy

A method of treating a silicon surface of a substrate that includes heating the substrate in a process chamber to a temperature, exposing a first area adjacent to the silicon surface to a first gas mixture comprising an etchant, a silicon source gas, and a carrier, exposing a second area adjacent to the silicon surface to a second gas mixture, wherein the second gas mixture is different from the first gas mixture.

Apparatus and method for surface finishing a silicon film

We report on a commercially reproducible silicon wafer with a high-reflectance buried distributed Bragg reflector (DBR). The substrate consists of a two-period DBR fabricated using a double silicon-on-insulator (SOI) process. The buried DBR provides a 90% reflecting surface. We have fabricated resonant cavity-enhanced Si photodetectors with 40% quantum efficiency at 860 nm and a full-width at half-maximum of 29 ps suitable for 10 Gbps data communications. We have also implemented double-SOI substrates with 90% reflectivity covering 1300 and 1550 nm for use in Si-based optoelectronics.

Silicon substrates with buried distributed Bragg reflectors for resonant cavity-enhanced optoelectronics

Oxygen-implanted silicon-on-insulator (SOI) material, or SIMOX (separation by implantation of oxygen), is another chapter in the continuing development of new material technologies for use by the semiconductor industry. Building integrated circuits (ICs) in a thin layer of crystalline silicon on a layer of silicon oxide on a silicon substrate has benefits for radiationhard, high-temperature, high-speed, low-voltage, and low-power operation, and for future device designs. Historically the first interest in SIMOX was for radiation-hard electronics for space, but the major application of interest currently is low-power, high-speed, portable electronics. Silicon-on-insulator also avoids the disadvantage of a completely different substrate such as sapphire or gallium arsenide. Formation of a buried-oxide (BOX) layer by high-energy, high-dose, oxygen ion implantation has the advantage that the ion-implant dose can be made extremely precise and extremely uniform. However the silicon and oxide layers are highly damaged after the implant, so high-temperature annealing sequences are required to restore devicequality material. In fact SIMOX process development necessitated the development of new technologies for high-dose implantation and high-temperature annealing.

Maria Anc

Papers

Evolution and Future Trends of SIMOX Material