Fabrication of UV-Sensitive SiC Diode by Laser Processing

(1) 1999年的研究结果(a)用脉冲准分子激光（KrF）处理方法在100 Torr的恒压条件下对n型6H-SiC掺杂的al深度剖面进行了评价，激光脉冲数从1000次到8000次不等。它们被近似为两个互补误差函数的和；靠近表面的分布在10 ~ 30 nm之间，而靠近内部的分布（尾部分布）在20 ~ 100 nm之间。研究表明，根据激光脉冲数的不同，铝的深度曲线可以控制在20 ~ 100 nm之间。部分掺杂铝在没有任何后处理的情况下被电激活，并且通过霍尔效应和I-V测量证实了p型导电。在E_v+0.239 eV时，al受体水平也被PL测量证实。(b)用脉冲激光处理W/Ti和Al/Ti分别与n型和p型6H-SiC衬底的欧姆接触。对于n型和p型衬底，电极表面非常光滑，接触电阻率分别为6.7x10^<-5>和1x10^<-3> Ωcm^2。与高温热处理相比，接触界面区域非常薄。(2) 2000年(a) KrF准分子激光脉冲处理n型6H-SiC掺杂的Al-depth谱图再次确认了0 ~ 20 nm和20 ~ 100 nm两个区域的分布，用互补误差函数的和近似。在保持激光脉冲能量密度为1.2J/cm^2和激光照射次数为1000的条件下，TMA/H_2气体压力分别为10、100和200 Torr时，曲线拟合得到的表面Al浓度分别为9.0 × 10^<17>、4.5 × 10^<18>和2.7 × 10^<19> Al/cm^3。研究表明，利用TMA/H_2气体压力、激光能量密度和激光发射次数三个参数可以控制al深度分布。(b)在TMA/H_2条件下，在未掺杂的N型6H-SiC （2.5x10^<115> N/cm^3）上制备了薄pn结二极管；100托尔，No。射击；和1.2J/cm^2。在p型掺杂层上采用薄Al/Ti欧姆接触，在330nm波长处，光响应率最高，外量子效率为41%。少

(1) Results in 1999(a) Al-depth profiles in n-type 6H-SiC doped with a pulsed excimer laser (KrF) processing method under the conditions of a constant pressure 100 Torr of the hydrogen-diluted TMA (trimethylaluminum) have been evaluated varying a number of laser pulses from 1000 to 8000 shots. They were approximated as sum of two complimentary error-functions ; the one nearer to surface ranging from 10 to 30 nm and the other inner one (tail distribution) from 20 to 100 nm. The investigations show that the aluminum depth profiles could be controlled between 20 and 100 nm according to the number of the laser pulses. A fraction of doped Al was electrically activated without any post heat treatments, and p-type conduction was confirmed with Hall effect and I-V measurements. Al-acceptor levels at E_v+0.239 eV was also confirmed with PL measurements.(b) Ohmic contacts with W/Ti and Al/Ti to n- and p-type 6H-SiC substrates, respectively, have been refined with a pulsed laser processing using … More KrF excimer laser. The electrodes have very smooth surfaces and the contact resistivity of 6.7x10^<-5> and 1x10^<-3> Ωcm^2 for n- and p-type substrate, respectively. The contact interface regions are very thin comparing with the one produced with heat treatments at high temperature.(2) Results in 2000(a) Al-depth profiles in n-type 6H-SiC doped with a pulsed laser processing using a KrF excimer laser have reconfirmed the distribution of the both regions of 0 to 20 nm and 20 to 100 nm, which are approximated with the sum of the complimentary error-function. The surface Al concentrations estimated from the curve fitting are 9.0x10^<17>, 4.5x10^<18>, and 2.7x10^<19> Al/cm^3 for the respective gas pressure of TMA/H_2 10, 100, and 200 Torr, keeping constant an energy density of the laser pulse 1.2J/cm^2 and a number of laser shots 1000. The present investigations confirmed that Al-depth profiles could be controlled with three parameters such as the TMA/H_2 gas pressure and the laser energy density, and a number of laser shots.(b) Thin pn junction diodes have been fabricated on the undoped n-type 6H-SiC (2.5x10^<115> N/cm^3) under the following conditions, TMA/H_2 ; 100 Torr, No.of shots ; 8000, and 1.2J/cm^2. Using a thin Al/Ti ohmic contact on the P-type doped-layer, the photo-responsivity has maximum external quantum efficiency 41% at the wavelength of 330 nm. Less