Luis Selva

Proton degradation of light-emitting diodes

Proton degradation is investigated for several types of light-emitting diodes with wavelengths in the near infrared region. Several basic light-emitting diode (LED) technologies are compared, including homojunction and double-heterojunction devices. Homojunction LEDs fabricated with amphoteric dopants are far more sensitive to displacement damage than double-heterojunction LEDs, and are strongly affected by injection-enhanced annealing. Unit-to-unit variability remains an important issue for all LED technologies. For technologies, degradation of the forward voltage characteristics appears to be more significant than degradation of light output.

Displacement damage-induced catastrophic second breakdown in silicon carbide Schottky power diodes

A novel catastrophic breakdown mode in reverse biased silicon carbide diodes has been seen for particles that are too low in LET to induce SEB, however SEB-like events were seen from particles of higher LET. The low LET breakdown mechanism correlates with second breakdown in diodes due to increased leakage and assisted charge injection from incident particles. Percolation theory was used to predict some basic responses of the devices.

On the role of energy deposition in triggering SEGR in power MOSFETs

Single event gate rupture (SEGR) was studied using three types of power MOSFET devices with ions having incident linear energy transfers (LETs) in silicon from 26 to 82 MeV/spl middot/cm/sup 2//mg. Results are: (1) consistent with Wrobels oxide breakdown for V/sub DS/=0 volts (for both normal incidence and angle); and (2) when V/sub GS/=0 volts, energy deposited near the Si/SiO/sub 2/ interface is more important than the energy deposited deeper in the epi.

Sensitivity to LET and Test Conditions for SEE Testing of Power MOSFETs

The results of recent Single Event Gate Rupture and Single Event Burnout testing on power MOSFETS are presented. The recent test data show a considerable drop in failure voltage in comparison to manufacturer data for device ratings over 130V. The effect of range is considered to account for this difference. The methods and practices for testing and data analyses that need to be used for adequate SEE testing of power MOSFETs are also presented. I. INTRODUCTION any space applications are demanding more power and higher voltages. Unfortunately, the technology behind high blocking voltages in discrete devices is susceptible to radiation effects. The large feature sizes and low-doped regions of silicon are the underlying liable areas of these devices to radiation. The application of power devices can be especially stressful when power or voltage requirements are demanding, or the mission environment is hostile. Most power solutions for design approaches in space employ the vertical power MOSFET, but these devices present limitations and trade challenges to projects that require high speed or very large power for high current applications. This work presents the results from various testing of power MOSFETs with rigorous test conditions. This study aims to refine the methodology for adequate hardness assurance of power MOSFETs for space missions.

Catastrophic SEE in high-voltage power MOSFETs

Heavy ion irradiation of high-voltage power MOSFETs with long-range ions (>123/spl mu/m in silicon) was performed using 14, 19, 22, 24, 28, and 39 MeV-cm/sup 2//mg ions at normal incidence. Prior to catastrophic failure some DUTs exhibited unusual electrical characteristic: all devices demonstrated high current transients (or current spikes) at voltages significantly lower than the voltage at which the devices failed.

Current Leakage Evolution in Partially Gate Ruptured Power MOSFETs

It has been observed that power MOSFETs can experience an SEGR and continue to function with altered parameters. We propose that there are three different types of SEGR modes; the micro-break, the thermal runaway, and the avalanche breakdown. Data that demonstrates these stages of device failure are presented as well as a proposed model for the micro-break. Brief discussions of the other modes, based on analysis combined with our interpretations of the older literature, are also given.

Effect of Dose History on SEGR Properties of Power MOSFETS

We present data that show that proton radiation damage can influence the single event gate rupture response of a power MOSFET. A primary phenomenon of single event gate rupture, the drain to gate threshold at which single event gate rupture occurs, drops as a function of device dosage. The shift in the threshold voltage correlates the best with the drop in the voltage at which SEGR occurs. The increase in the field strength due to trapped charges within the oxide during a charge collection event is suspected as the mechanism.

Device SEE susceptibility update: 1996-1998

This eighth Compendium continues the previous work of Nichols, et al., on single event effects (SEE) first published in 1985. Because the Compendium has grown so voluminous, this update only presents data not published in previous compendia.

Effects of Radiation on Commercial Power Devices

The effects of radiation on various commercial power devices are presented. The devices have proved to be very fragile to single event effects, with some of the devices actually succumbing to catastrophic SEE with protons

SEGR/SEB Test Results on Emerging Hi-Rel Power MOSFETs

Test results for several newly available Hi-Rel total dose hardened power MOSFETs are presented. The safe-operating-area (SOA) of several devices were determined with Ag and Xe ions having incident LETs of 42.2 and 53.1 MeV cm 2 /mg, respectively. Test results show these devices are comparable to currently available total dose hardened technology.