Microwave losses of undoped n-type silicon and undoped 4H-SiC single crystals at cryogenic temperatures
Microwave losses of undoped n-type silicon and undoped 4H-SiC single crystals at cryogenic temperatures
复制标题
低温下未掺杂 n 型硅和未掺杂 4H-SiC 单晶的微波损耗
DOI：
--
复制
发表时间：
2014
影响因子：
2.4
通讯作者：
Sang Young Lee
中科院分区：
文献类型：
--
作者：
H. Jung;W. Yang;M. Cho;Kee Nam Joo;Sang Young Lee
为了提高测量灵敏度，采用高tc超导体YBa2Cu3O7-δ薄膜作为介质谐振腔，研究了8.6-24 GHz低温下单晶Si和4H-SiC的微波损耗。我们的未掺杂n型Si的损耗切线在低于20 K的温度下表现得非常低，在10 K时24 GHz的值为1 × 10−6，比Krupka等人报道的在10 K时6.8 GHz的值2 × 10−4低100多倍。Microw。无机材料学报，1999,19(6):444 - 444。同时，原始4H-SiC的损耗正切值非常高，在8.6 GHz下10 K时达到0.01，是未掺杂Si的4000倍。当原始的4H-SiC用热中子辐照时，由于电阻率显著降低，损耗切线提高了7倍。我们的研究结果表明，在低于20 K的温度下，未掺杂的n型Si的损耗切线足够低，可以用于各种低温应用，并且热中子辐照可以通过中子突变掺杂提供降低SiC电阻率的有用手段。
We investigated microwave losses of single-crystalline Si and 4H-SiC at cryogenic temperatures at 8.6–24 GHz using a method involving a dielectric resonator with high-Tc superconductor YBa2Cu3O7-δ films used to improve the measurement sensitivity. The loss tangent of our undoped n-type Si appeared to be extremely low at temperatures below 20 K with a value of 1 × 10−6 at 24 GHz at 10 K, which is more than 100 times lower than the value of 2 × 10−4 at 6.8 GHz at 10 K reported by Krupka et al. [IEEE Trans. Microw. Theory Tech. 54, 3995 (2006)] for undoped p-type Si. Meanwhile, the loss tangent of pristine 4H-SiC appeared to be very high with a value of 0.01 at 10 K at 8.6 GHz, which is 4000 times higher than that of our undoped Si. When the pristine 4H-SiC was irradiated with thermal neutrons, the loss tangent was enhanced by seven times due to the significantly reduced electrical resistivity. Our results show that, at temperatures below 20 K, the loss tangent of undoped n-type Si is low enough for various cryogenic applications and that thermal neutron irradiation could provide a useful means of reducing the electrical resistivity of SiC possibly by means of neutron transmutation doping.