Radiation effects on semiconductor devices

The radiation-induced degradation of semiconductor material parameters is reviewed. These results are related to the degradation of semiconductor-device performance. Design techniques for minimizing the radiation-induced degradation are evaluated. Emphasis is placed on the effects of neutron-produced displacement damage on devices and on the effects of ionizing radiation on MOS structures. Transient ionization effects and circuit latchup are considered. The present degree of understanding of radiation effects in silicon devices is summarized.     

Skin-inspired electronics:emerging semiconductor devices and systems

Current electronics are driven by advanced microfabrication for fast and efficient information processing.In spite of high performance,these wafer-based devices are rigid,non-degradable,and unable to autonomous repair.Skin-inspired electronics have emerged as a new class of devices and systems for next-generation flexible and wearable electronics.The technology gains inspiration from the structures,properties,and sensing mechanisms of the skin,which may find a broad range of applications in cutting-edge fields such as healthcare monitoring,human-machine interface,and soft robotics/prostheses.Practical demands have fueled the development of electronic materials with skin-like properties in terms of stretchability,self-healing capability,and biodegradability.These materials provide the basis for functional sensors with innovative and biomimetic designs.Further system-level integrations and optimizations enable new forms of electronics for real-world applications.This review summarizes recent advancements in this active area and speculates on future directions.     

Optimum semiconductor for microwave devices

The best semiconductors for microwave devices, silicon and gallium arsenide, are restricted in their performance because the electron drift velocity saturates at a fairly low value. It is proposed that InAs-InP alloys should give better performance. Detailed calculations of drift velocity are made by a Monte Carlo technique, and it is shown that some alloys should give drift velocities greater than 4×107cm/s.     

Microelectrodes for contacting semiconductor devices

Finely pointed wires are useful for contacting semiconductor devices, for field emitters and biomedical microprobes. An `electronic pencil sharpener? has been developed in which a wire is shaped into a sharp point using spark erosion. The wires with a tip radius of 0.5?1 ?n are highly suitable contacts to Schottky mixer diodes.     

The space radiation environment for electronics

The Earth's space radiation environment is described in terms of charged particles as relevant to effects on spacecraft electronics. The nature and magnitude of the trapped and transiting environments are described in terms of spatial distribution and temporal variation. The internal radiation environment of the spacecraft is described in terms of shielding the high-energy particles of the free-field environment. Exposure levels are presented in terms of ionizing radiation dose and particle fluence for comparison to electronic component susceptibility     

Microjet cooling devices for thermal management of electronics

This research is an effort to demonstrate the applicability of miniaturized synthetic jet (microjet) technology to the area of thermal management of microelectronic devices. Synthetic jets are jets which are formed from entrainment and expulsion of the fluid in which they are embedded. Design issues of microjet cooling devices are discussed along with characterization of excitation elements and the turbulent synthetic jets produced thereby. Geometrical parameters of the microjet cooling devices were empirically optimized with regards to cooling performance. The cooling performance of the optimized microjets was compared with previous theoretical and empirical studies of conventional jet impingement. The cooling performance of the microjet devices has been investigated in an open environment as well as in a vented and closed case environment. In such experiments, the synthetic jet impinges normal to the surface of a packaged thermal test die, comprising a heater and a diode-based temperature sensor. This test assembly allows simultaneous heat generation and temperature sensing of the package, thereby enabling assessment of the performance of the synthetic jet. Using microjet cooling devices, a thermal resistance of 30.1/spl deg/C/W has been achieved (when unforced cooling is used, thermal resistance is 59.6/spl deg/C/W) when the test chip is located at 15mm spacing from the jet exit plane. In order to more directly compare and scale the cooling results, a preliminary study on heat transfer correlations of the microjet cooling device has been performed. Finally, a comparison of the performance of the microjet cooler with standard cooling fans is given.     

Ion-implanted semiconductor devices

Ion implantation is finding increased usage in device fabrication owing to precise control and reproducibility of the charge and depth distribution of the implanted-dopant profile. The MOST illustrates the application of charge control through threshold-voltage adjustment and though predepostion for drive-in diffusion to form complementary devices. A compilation of range-energy data for B, P, and As in silicon is given along with factors which influence the implanted-dopant distributions after anneal treatments. Implantation procedures are presented for high-frequency bipolar transistors which depend critically on both charge and depth control of the emitter and base profiles. Another important aspect of ion implantation is lateral control, a feature which is necessary for high packing density circuits. Disorder effects associated with implantation through oxide masks are discussed. A brief account of implantation for GaAs devices is also included.     

Power semiconductor devices for variable-frequency drives

Advances in power semiconductor technology are the driving force for enhancement of the performance of variable-frequency motor drives. The development of power semiconductor devices with MOS-gate structures has enabled the control of large amounts of energy with very little input power. An equally important advancement has taken place in the development of improved rectifiers with reduced losses for high-frequency operation. In addition, the advent of MOS-gated power switches has led to the creation of smart power technology which makes compact systems with built-in diagnostic and protection functions commercially feasible. Although the power semiconductor chips are all made from silicon today, recent analysis has indicated that devices fabricated from silicon carbide have the potential for completely displacing silicon devices in the long range     

Reliability of semiconductor devices for submarine-cable systems

The Bell System initiated development of semiconductor devices for use in broad-band repeatered coaxial submarine-cable telephone systems in the early 1960's. Development of such devices has continued at varying levels of activity to this date. Now, over a decade later, more than five years of successful operational life have elapsed on the first installed system; one transatlantic system is in operation and several more of equal or greater length are in various stages of construction. Laboratory-like life validation tests have been conducted on all the devices for use in these systems, and up to seven years of history have elapsed on groups of 100 devices representative of the five varieties used in the first system. No failures have been observed either in service or in life validation tests, thereby confirming a FIT rate of better than five. Moreover, variables data for the representative samples aged for seven years indicate that the confirmed FIT rate may be extremely conservative. Silicon diodes aged below breakdown are more stable than the life-test system designed to evaluate their reliability. Silicon diodes aged in breakdown show a linear drift in leakage current which is so small that it is not detectable except with an ultrasensitive test system. Germanium transistors evaluated over this same period show that the change in current gain they exhibit will be substantially less than the goal established for them at the inception of development. Silicon transistors being developed for a new higher capacity system show promise of exceeding the stability of the more extensively evaluated germanium devices. These results have broader implications than their relevance to submarine-cable system performance since they indicate that the reliability which has long been considered to be inherent in semiconductor devices not only has been demonstrably achieved in quantitative terms but can be considered to be designable for future system applications.     

Techniques for small-signal analysis of semiconductor devices

Techniques for ascertaining the small-signal behavior of semiconductor devices in the context of numerical device simulation are discussed. Three standard approaches to this problem will be compared: (i) transient excitation followed by Fourier decomposition, (ii) incremental charge partitioning, and (iii) sinusoidal steady-state analysis. Sinusoidal steady-state analysis is shown to be the superior approach by providing accurate, rigorously correct results with reasonable computational cost and programming commitment.     

Nonvolatile semiconductor memory devices

An attempt is made to survey and assess the nonvolatile semiconductor memory devices including charge-storage devices and FET's with ferroelectric gate insulators. The charge-storage devices are further divided into two groups: 1) charges-trapping devices such as the MNOS and the MAOS, and 2) floating-gate devices such as the FAMOS and the DDC. Approaches for achieving virtual nonvolatility in otherwise volatile semiconductor memories are briefly disscused. Novel structures which provide nonvolatility as well as the theoretical limit of memory array density are also explored.     

Electron bombarded semiconductor devices

The first electron bombarded semiconductor (EBS) devices have recently appeared on the market. These devices have already demonstrated that EBS has considerable promise as an important new electron device for power amplification and control. EBS devices are described with particular emphasis on power devices. The basic EBS principle, some of the analysis used in device design, general considerations in designing the various elements of the device, overall device design, semiconductor processing, and reliability considerations are discussed. Predictions of general directions for future work are made. Some historical information is also presented as well as a brief comparison with other competing power devices.     

Active semiconductor microdisk devices

The design of active semiconductor microdisk switches, modulators, or wavelength routers enabled by modulating the transfer characteristics of a resonant cavity is investigated. A simple theoretical model based on coupled-mode theory is used to elucidate design trends and constraints in the cases where electroabsorption, gain, and free carrier injection are employed to modulate the resonator characteristic     

Single nanoparticle semiconductor devices

Using a new technique in forming the cubic single-crystal silicon nanoparticles that are about 40 nm on a side, the authors have demonstrated a vertical-flow surround-gate Schottky-barrier transistor. This approach allows the use of well-known approaches to surface passivation and contact formation within the context of deposited single-crystal materials for device applications. It opens the door to the novel three-dimensional integrated circuits and new approaches to hyper integration. The fabrication process involves successive deposition and planarization and does not require nonoptical lithography. Device characteristics show reasonable turn-off characteristics and on-current densities of more than 10/sup 7/ A/cm/sup 2/.     

Progress in silicon carbide semiconductor electronics technology

Silicon carbide’s demonstrated ability to function under extreme high-temperature, high-power, and/or high-radiation conditions is expected to enable significant enhancements to a far-ranging variety of applications and systems. However, improvements in crystal growth and device fabrication processes are needed before SiC-based devices and circuits can be scaled-up and incorporated into electronic systems. This paper surveys the present status of SiC-based semiconductor electronics and identifies areas where technological maturation is needed. The prospects for resolving these obstacles are discussed. Recent achievements include the monolithic realization of SiC integrated circuit operational amplifiers and digital logic circuits, as well as significant improvements to epitaxial and bulk crystal growth processes that impact the viability of this rapidly emerging technology.     

Bulk negative-resistance semiconductor devices

Recent research on semiconductors that exhibit bulk negative resistivity has led to new devices for pulse regeneration, logic function generation, amplification, and millimeter-wave power generation. These are bulk devices in the sense that ac gain is derived from the bulk negative-resistance property of certain uniform semiconductors, rather than from the properties of junctions between different types of semiconductors. Bulk devices are capable of operating with more power at higher speeds and frequencies than conventional junction devices such as transistors.