Hidenobu Mori

Development of a new data collection system and chamber for microbeam and laser investigations of single event phenomena

Abstract A new target chamber and control system for temperature-based transient-IBIC and transient-LBIC measurements using the same experimental chamber is outlined. The system has been designed for both ultra-fast and relatively slow transient measurements as a function of temperature from 77 K to 450 K. The control system, implemented in the Labview environment, allows single ion scanning and transient acquisition on a set of oscilloscopes, for an array of temperatures and bias. The modularity of the system allows its use for a broad range of experiments from single event upset transient current measurements to scanning ion deep level transient spectroscopy charge transient measurements. In this paper, we describe the overall system and illustrate its potential by way of example.

Displacement damage degradation of ion-induced charge in Si pin photodiode

Abstract Photonic devices operating in space must exhibit high-radiation hardness due to prolonged exposure to high-energy radiation fields. The device performance can be influenced by both the transient effect of electron–hole plasma generation due to stopping of high-energy particles, and the accumulated effect of damage introduced by a flux of particles. The complex relationship between the two is an increasingly important area of research. Here we investigate charge collection characteristics of in situ ion beam induced damaged samples by measuring single event transient currents induced by heavy ions. Results from this study suggest that the ion-induced charge degradation can be predicted for any ion species and energy using the concept of non-ionizing energy loss and displacement damage dose.

TCAD modeling of single MeV ion induced charge collection processes in Si devices

Abstract Single MeV ion induced currents are directly responsible for a wide range of single event phenomena leading to temporary or permanent malfunction of devices in radiation environments such as space. The active regions of a device act as a source of transient currents injected into a device subsystem by collecting the charge induced by MeV ions. As such, the charge collection process is an important step in understanding mechanisms that lead to device malfunction. In this paper, we present transient current data collected on Si epilayer devices with 15 MeV O4+ ions focused using a MeV heavy ion micro-probe. The measured transient currents are compared to quasi-3D simulation using ISE TCAD software. Critical factors influencing the fidelity of the measurement technique and modeling of heavy ion track models are also discussed.

Studies on single-event phenomena using the heavy-ion microbeam at JAERI

A single-event upset (SEU) is triggered when the amount of charge induced by an energetic ion striking a sensitive area exceeds a critical charge within a given time interval. An accurate understanding of the charge collection processes that give rise to SEU is critical for the design of SEU tolerant microelectronic devices. The best method for clearly examining charge collection during an SEU is to examine the ultra-fast current transient waveform. This is best achieved by a heavy-ion microbeam in combination with an ultra-fast sampling oscilloscope. In the past there have been numerous experiments aimed at directly measuring the ultra-fast current transient induced in various diodes by single ion strikes. The aim has been to examine the effect of charge collection components such as drift, funneling and diffusion on the SEU processes. In this paper, we present a summary of various experiments using the newly developed transient ion beam induced current system developed at JAERI.

A comparison of heavy ion and picosecond laser microbeams for investigating single event transients in InGaAs on InP photodetectors

The MeV ion and laser microbeams are the two most commonly used tools for examining the spatial and temporal dependence of charge collection processes that lead to single event phenomena in semiconductor devices. In this paper, we perform a detailed comparison of the fundamental differences that exist between the two methods for examining single event transients in InGaAs photodetectors. In particular, we compare results collected by transient laser and ion beam induced current for several ion species.

Investigation of single-event charge collection from angled ion strikes

Abstract Single-event upsets (SEUs) are a major concern for dynamic random access memory (DRAM) and static random access memory (SRAM) installed in space-based satellites. Recently, large-scale integration of memory devices has made them even more susceptible to multiple-bit upsets (MBUs). MBU generally results when an ion strike passes through, or interferes with, multiple memory cells at the same time. However, the fundamental processes behind MBU have not yet been fully clarified. In order to investigate the mechanism of MBU, we examined the relationship between the amount of the collected charge and the angle of the incident ion to the test device.

Investigation of radiation degradation of Si and GaAlAs optical devices due to gamma-ray and electron irradiation

Abstract We have investigated the degradation of optocoupler components, i.e., Si p + –i–n photodiodes and GaAlAs LEDs, under gamma and electron irradiations. The results can be explained with a decrease in the minority carrier lifetime caused by the formation of defects during irradiations. Degradation of the electrical characteristics of p + –i–n photodiodes was found to be significant in comparison with that of LEDs. It suggests that the degradation of p + –i–n photodiode becomes dominant in radiation degradation of optocoupler.

Study of single-event current pulses induced in SOI diodes by collimated swift heavy-ions micro-beams

Abstract We have succeeded in measuring single-event current pulses in silicon-on-insulator (SOI) structures using collimated heavy-ion beams in conjunction with a wide-bandwidth current–pulse measurement system. The total amount of collected charges for ions incident on the p+n junction indicate collection from below the top silicon layer in the SOI diode. For such high energies, SOI structures were found to be an ineffective means for ensuring the radiation hardness of electronic devices used in space.

Comparison of the ion induced charge collection in Si epilayer and SOI devices

Abstract It is known that the single-event phenomena (SEP) are the malfunction of micro electronics devices caused by the impact of an energetic heavy ion. Improving the tolerance of devices to the SEP requires a better understanding of basic charge collection mechanisms on the timescales of the order of picoseconds. In order to better elucidate these mechanisms, we measure the fast transient current resulting from heavy ion strikes with a fast sampling data collection system and a heavy ion microbeam line at JAERI. In this paper we report on differences in both the transient current and charge collection from 15 MeV carbon ions on silicon-on-insulator, Si epilayer and bulk p + n junction diodes and charge transportation under MeV ion injection is discussed.

Estimation of fast transient current degradation analyzed by non-ionizing energy loss

Abstract In recent years, special interests have been paid to the advantage of using III–V compound semiconductors for the microelectronic and optoelectronic industries because of its high-speed response. Ion beam induced charge (IBIC) and transient-IBIC techniques are useful in order to investigate the single event effects, which is one of the most serious problems to use semiconductor devices in space. During image collection, the ion-induced damage is introduced. Therefore the degradation behavior of collected charge and transient current are important issue to use these techniques most effectively. To estimate degradation behavior, the damage factors of InGaAs devices are compared with that of Si devices by using the concept of non-ionizing energy loss.