SiC-Based Detectors of Particles
Study of SiC Irradiated with High Energy Particles to Create High-Temperature Radiation-Resistant Detectors of the Ions and Nuclear Particles
Tech Area / Field
- PHY-SSP/Solid State Physics/Physics
- INS-DET/Detection Devices/Instrumentation
- PHY-ANU/Atomic and Nuclear Physics/Physics
3 Approved without Funding
Russian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg
- NIIIT (Pulse Techniques), Russia, Moscow\nNuclear Physics Institute, Russia, Leningrad reg., Gatchina\nJoint Institute of Nuclear Research, Russia, Moscow reg., Dubna
- University of Erlangen-Nurnberg / Instittut fuer Angewandte Physik, Germany, Erlangen\nRoyal Institute of Technology / Department of Microelectronida & IT, Sweden, Kista
Project summaryThe main objective of this project is the study of the SiC radiation hardness and elaboration of SiC radiation-resistant detectors for registration and spectrometry of high-energy ions, nuclear particles and thermal neutrons stably operating at high temperatures.
Silicon carbide is one of the most promising wide band gap semiconductors with excellent electrical and mechanical properties as well as high temperature, chemical and radiation stability. Due to this unique set of properties it is possible to use SiC for fabrication of electronic devices capable to operate under extreme conditions. In particular, SiC is considered as a perspective material for cosmic electronics, devices for the control of nuclear materials dissemination and spent nuclear fuel checking, high-temperature radiation-resistant detectors of high energy particles. Additionally, SiC attracts attention as a candidate material for radio-frequency windows in thermonuclear reactors and as inert matrix fuel host in technology of highly radioactive waste utilization.
Recently, significant progress in the growth of high purity epitaxial SiC layers with low concentrations of deep-level centers and, respectively, high charge carrier lifetimes have been reached. This successful development the production of large SiC epitaxial layers (up to 3 inch in diameter) with different thickness allows an industrial production of a new generation of high performance devices. To evaluate the radiation tolerance of these devices, however, a systematic study of radiation damages in pure epitaxial layers is required.
First experiments aimed at characterization of electrical properties of 4H-SiC epitaxial layers with concentration of uncompensated donors Nd-Na=(3-5)ґ1015 cm-3 irradiated with a-particles, fast neutrons, Kr and Bi ions with energies of 1-3.5 MeV/nucleon have been undertaken at the Ioffe Institute in collaboration with JINR and PNPI. Radiation-induced changes in virgin material and devices based on it have been studied using Schottky barriers and high-voltage ion implanted diodes, formed by original technology developed at the Ioffe Institute. One of the main findings of this study was the possibility to increase the radiation hardness of devices based on SiC by raising the operating temperature. It was also revealed that the diode structures, that had been degraded after irradiation with fast neutrons and high-energy heavy ions, recovered their properties at the temperature of 500 °C. Therefore, the radiation resource and lifetime of such devices could be considerably increased that is actual problem.
Referring to these preliminary results, the SiC detectors based on Schottky barriers and ion implanted p-n junctions seems to be very attractive for the use in nuclear engineering and space electronics under conditions of high temperatures and strong radiation fields. At the same time, the widespread implementation of SiC based detectors and devices suggests more detailed studies of effects of different types of ionizing radiation: electrons, neutrons, light and heavy ions in a broad range of ion mass and energies as well as irradiation temperatures.
To achieve the main objective we propose to perform, for the first time, the following experiments:
1. To study the effect of irradiation with electrons, neutrons, light and heavy ions (from H to Bi) with high energy (from units to several hundred MeV) on the structural, optical and electrical characteristics 4H, 6H, 3C and 15R SiC polytypes of n-type conductivity in a wide range of uncompensated donor concentrations (from 1014 to 1019 cm-3). Irradiation experiments will be carried out at temperatures from 80 to 900 K. The Schottky barriers and ion implanted p-n junctions, formed in SiC by original technology developed at the Ioffe Institute, will be subjected to comparative electrical measurements in virgin and irradiated samples. Electrical characteristics will be examined in the temperatures range of 80 - 900 K.
2. An investigation of the processes of generation and annealing of structural defects enhanced by irradiation of SiC samples with different high energy particles. The annealing processes of radiation damages will be studied up to 2200 K. The results of these experiments, taking into account the data obtained from Item 1, are very important to gain a better understanding of the long-term and dose stability of parameters of detectors and devices during operation at temperatures up to 900 K.
3. To study the effect of technological conditions for creating Schottky barriers and ion implanted p-n junctions based on different SiC polytypes and how this affects their performance as high temperature detectors of various high energy nuclear particles and thermal neutrons. The deposition technology of the 6LiF thin-film covering used as envelope of thermal neutrons in charged particles to SiC detector structures. The mechanisms for charge generation and signal formation in nuclear radiation detectors will be investigated at temperatures up to 900 K. Particular attention will be paid to following measurements:
- the signal/noise ratio and the revelation of the main factors affecting this parameter;
- the current sensitivity and linearity of current characteristics in detectors depending on type, energy, intensity and dose of the ionizing irradiation;
- the charge collection efficiency and the energy resolution of detectors in wide range of irradiation temperatures and energies of the nuclear particles;
- the time resolution and current characteristics of detectors in subnanosecond range.
The main results of this project are expected to be as follows:
- data for formation of defects in different n-SiC polytypes with different majority carrier concentration, depending on particle energy spectrum, irradiation temperature, level of nuclear and ionizing energy losses of irradiating particles;
- data on radiation hardness of SiC detectors under high energy heavy ion irradiation, simulating the effect of heavy-ion component of cosmic radiation;
- data on correlation between the energy of defect formation and dark current of devices that will help to predict the radiation hardness of devices based on SiC;
- values of the maximum permissible doses of different types of irradiation for SiC, depending on temperature.
The prototypes of SiC nuclear detectors based on Schottky barriers and ion implanted p-n junctions, effectively working in intense radiation fields and high temperatures, will be created.
Scope of activities.
Four main interrelated tasks will be performed under project implementation:
- elaboration of advanced technology based on chemical vapor deposition (CVD) method to grow epitaxial n-SiC layers with electrical parameters required for creation of detectors of high energy ions and nuclear particles;
- experimental study of radiation-induced damage formation in 4H, 6H, 3C and 15R SiC polytypes on dependence of the temperature, particle type, intensity and dose rate;
- study of defect structure evolution in above SiC samples under annealing;
- creation of the prototypes of SiC nuclear and thermal neutrons detectors based on Schottky barriers and ion implanted p-n junctions; an investigation of the main detector parameters.
Technical Approach and Methodology.
To grow epitaxial n-SiC layers with electrical parameters required for creation of high energy ions and nuclear particles detectors, we suggest to use chemical vapor deposition (CVD) method. Test structures, which are Schottky barriers and ion implanted p-n junctions, will be formed by using original technology, developed at the Ioffe Institute. To create the prototypes of high energy ions and nuclear particles detectors, accounting the inpidual particle response, new technology of Schottky barriers and ion implanted p-n junctions with reverse bias voltage up to 3000 V and reverse current less than 10-7 А, will be elaborated. Virgin SiC material of different polytypes and concentration of uncompensated donors, diode test structures and detector prototypes will be irradiated with neutrons in nuclear reactor (PNPI), high energy (from units MeV to hundred MeV range) light and heavy ions (from Helium to Bismuth) on U-400 and IC-100 cyclotrons (JINR) at temperatures of 80-900 K. For experimental simulation of heavy-ion component of cosmic radiation effect it is suggested to use low intensity (103 ion/s-cm2) heavy ion beams. The annealing of radiation defects will be performed up to temperature of 2200 K. To characterize main parameters of material and diode structures before and after irradiation, and after heat treatments, more than 20 wide spread experimental techniques as well as complicated analytical and other special methods, developed in organizations- project participants, will be used. The temperature range of electrical measurements will be 80-900 K. Some of optical and electrical measurements will be carried out “in-situ”, immediately under irradiation. Thus, the above approach and methods intended to this project are highly competitive with scientific and technological world level.
Project participants – defense scientists:
PTI – Project participants have got wide experience both in the growth and integrated studies of various SiC polytypes and in the device creation, based on it. They have elaborated and implemented technologic processes for forming the Schottky barriers, low-resistance contacts, mesa-structures, ion-implanted low-resistance thin p- layers to be used in devices as a high-performance emitters. The devices based on SiC have been created for application both in space electronics and in high temperature working apparatus.
JINR – Project participants of Flerov Laboratory of Nuclear Reactions have got wide and long-term experience in irradiation of insulators, semiconductors and electronic components with ions of wide mass and energy ranges at cyclotrons. The experiments are carried out at cyclotron ion beam leading lines from the accelerator to the user irradiation chambers equipped with ion beam scanning system in horizontal and vertical directions and all necessary elements for ion beam parameters evaluation and control. In addition, the project participants have got abundant experience in “in-situ” characterization of insulators and semiconductors under ion beam irradiation as well as postirradiation measurements.
PNPI – Project participants have got wide experience in creation of semiconductor detectors and spectrometers for nuclear physics purposes as well as in studies of radiation defects in various semiconductor materials. The devices with high field-performance data created by them have permitted to carry out series of unique experiments and to solve some significant practical problem, for instance, the b-radiation registration at satellites in the space, g-radiation of nuclear-waste disposal and in environment at nuclear power plants control and monitoring. Significant part of radiation defect studies has been performed in a close connection with researches of radiation hardness of silicon based electronic components used in space electronics and under high energy proton irradiation.
NIIIT – Project participants are experienced specialists in research and development of devices and equipment for nuclear radiation registration and control of nuclear set-up parameters in view of elaboration of transformers, working in a hard radiation and thermal conditions, and unique analog-digital equipment.
Foreign Collaborators - Academic Director, professor Gerhard Pensl, Institute of Applied Physics, Germany, and Anders Hallen, Assistant Professor, Royal Institute of Technology, Sweden, in collaboration with PTI took an active part in INTAS project of research and development of high-power diodes based on ion-implanted SiC. Results of that project were highly rated by reviewers. At present time, scientific relations are continuing and joint experiments are under progress yielding many joint publications. This project intends the growth of high pure epitaxial SiC layers as an investment of collaborators and carrying out of joint experiments, seminars, discussions and publications.