Ion Microprobe Study of the Polarization Quenching Techniques in Single Crystal Diamond Radiation Detectors

Abstract

Synthetic single crystal diamond grown using the chemical vapor deposition technique constitutes an extraordinary candidate material for monitoring radiation in extreme environments. However, under certain conditions, a progressive creation of space charge regions within the crystal can lead to the deterioration of charge collection efficiency. This phenomenon is called polarization and represents one of the major drawbacks associated with using this type of device. In this study, we explore different techniques to mitigate the degradation of signal due to polarization. For this purpose, two different diamond detectors are characterized by the ion beam-induced charge technique using a nuclear microprobe, which utilizes MeV energy ions of different penetration depths to probe charge transport in the detectors. The effect of polarization is analyzed by turning off the bias applied to the detector during continuous or discontinuous irradiation, and also by alternating bias polarity. In addition, the beneficial influence of temperature for reducing the effect of polarization is also observed. Finally, the effect of illuminating the detector with light is also measured. Our experimental results indicate that heating a detector or turning off the bias, and then applying it during continuous irradiation can be used as satisfactory methods for recovering the CCE value close to that of a prepolarized state. In damaged regions, illumination with white light can be used as a standard method to suppress the strength of polarization induced by holes.

Direct current mode neutron detection, investigation of polarization effect on 500 μm single crystal CVD diamond detector, and depolarization techniques

“…However, the external field is not strong enough to de-trap carriers from trap sites, which causes fluctuating internal electric field and instability in the measured detector current. An additional increase in bias will give it sufficient strength to de-trap carriers, which could limit the effect of polarization [9]. Furthermore, increase in dark current is caused by late relaxing carriers.…”

“…Assuming similar composition with natural diamond, the isotopic abundance of CVD diamond is 98.93% carbon-12 ( 12 C) and 1.07% carbon-13 ( 13 C) [5]. Both 12 C and 13 C could capture a neutron and absorb its energy, the most prominent reactions of which are 12 C(n,) 9 Be, 12 C(n, n+2) 4 He, and 13 C(n,) 10 Be, which yield 6 -10 MeV per interaction [6]. Additionally, neutrons could elastically scatter off 12 C and 13 C atoms, which deposits 1.8 to 2.0 MeV per interaction.…”

“…However, in a practical detector, charge carriers often can get trapped at various defect sites such as: inclusions, grain boundaries, and plane dislocations in the diamond bulk [9 Besides the detection mechanism by its principles creates further inclusions, vacancies and damages.]. Several reports indicate that the density of traps in a SC CVD diamond detector increases progressively over a duration of each continuous use [7][8][9][10][11][12]. The accumulation of charges at defect sites as shown in Figure ( 1) could then result in an emergence of an internal electric field (E in ) between oppositely charged defect sites.…”

“…Consequently, a small variation in the net applied electric field has a pronounced effect on the reliability of the measurement. Reports have shown the strength and polarity of the applied electric field influences the trapping and detrapping dynamics of charge carriers [9][10][11]. Therefore, a study on the DC response of a SC CVD diamond neutron detector under various electric field values is necessary to understand the effect of measurement conditions on overall DC response of the detector.…”

CVD Encapsulation of Laser-Graphitized Electrodes in Diamond Electro-Optical Devices

“…Diamond is a unique material with a number of record-breaking properties. Its electrical breakdown threshold is up to 2-10 MV/cm [1][2][3], making it attractive for highvoltage applications, such as field electron transistors [4][5][6][7][8], switching diodes [9][10][11][12][13], highenergy particle trapping [14][15][16][17][18], photoconductive antennas [19][20][21][22] and others. The thermal conductivity of diamond (24 W/cm•K) [23] is even higher than that of copper, which allows it to effectively dissipate heat [24][25][26][27][28].…”