Charge collection efficiency study on neutron-irradiated planar silicon carbide diodes via UV-TCT

The high flux neutron irradiation has an impact on the charge collection efficiency(CCE) of SiC detectors.In this article,measurements were conducted on planar p-on-n diodes,which were manufactured on 4H−SiC wafers and were provided by CNM (Barcelona) .The total thickness of the wafers was 400 μm, including a 45–50 μm thick n-doped epitaxial active layer. The full depletion voltage was determined to be at 296 V via CV-measurements.The 4H−SiC pad sensors were placed in the dry irradiation channels, under neutron fluences of 5e14,1e15,5e15 and 1e16.The irradiated samples were subjected to I-V tests and UV-TCT (370nm) at room temperature.The results show that the leakage currents remained very low (below 14 nA) for all irradiation fluences at room temperature.Regarding the CCE, we observed a performance degradation worsening with increasing irradiation fluence,although the CCE could be partially compensated by the high applied voltage.While CCE was considered sufficient after lower irradiation fluences(<1e15neq∕cm2),it decreased drastically above.At the highest fluence of 1e16, no signals could be detected, possibly due the active layer becoming intrinsic, which is supported by the IV-characteristics of the samples.

Further reading:P. Gaggl,T.Bergauer,M.Göbel et al.,”Charge collection efficiency study on neutron-irradiated planar silicon carbide diodes via UV-TCT,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,Volume 1040,2022,167218,doi:10.1016/j.nima.2022.167218

对中子辐照后的平面型碳化硅探测器电荷收集效率的UV-TCT研究

高通量的中子辐照剂量会对SiC探测器的电荷收集效率产生影响。对CNM的4H-SiC探测器(SiC外延层45-50um,掺杂1.5e15)分别进行5e14、1e15、5e15、1e16剂量的中子辐照，对辐照后的样品进行室温下的I-V测试与UV-TCT(波长370nm)测试。测试结果显示辐照后的样品暗电流均保持较低水平(<14nA)，但电荷收集效率均明显降低，在较低辐照剂量(<1e15)以下，电荷收集效率可通过更高的反向偏置电压部分弥补，在更高的辐照剂量下，电荷收集效率急剧降低，在1e16辐照剂量下，由于活性层已变为本征层，TCT测试时没有信号产生。

延伸阅读：P. Gaggl,T.Bergauer,M.Göbel et al.,”Charge collection efficiency study on neutron-irradiated planar silicon carbide diodes via UV-TCT,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,Volume 1040,2022,167218,doi:10.1016/j.nima.2022.167218