Fabrication of UV-Sensitive SiC Diode by Laser Processing

(1)1999年的结果（a）在恒定压力100 Torr的氢稀释的TMA（三甲基铝）的条件下，用脉冲准分子激光（KrF）处理方法掺杂的n型6 H-SiC中的Al深度分布已经被评估为改变激光脉冲数从1000到8000次。它们近似为两个互补误差函数的和;一个更靠近表面，范围从10至30 nm，另一个内部误差函数（尾部分布）从20至100 nm。研究表明，铝的深度分布可以控制在20和100 nm之间，根据激光脉冲的数量。一部分掺杂的Al被电激活而无需任何后热处理，并且通过霍尔效应和I-V测量证实了p型导电。PL测量也证实了Al受主能级在E_v+0.239 eV。(b)用脉冲激光加工方法分别对W/Ti和Al/Ti与n型和p型6 H-SiC衬底的欧姆接触进行了细化， ...更多信息 KrF准分子激光器。电极具有非常光滑的表面，对于n型和p型衬底，接触电阻率分别为6.7 × 10 <-5>^ Ω cm ^2和1 × 10 ^<-3>Ω cm ^2。与高温热处理产生的接触界面区域相比，接触界面区域非常薄。(2)2000年的结果（a）用KrF准分子激光器脉冲激光加工掺杂的n型6 H-SiC中的Al深度分布再次证实了0至20 nm和20至100 nm两个区域的分布，它们近似于互补误差函数的总和。当<17><18><19>TMA/H_2的气压为10、100和200 Torr时，激光脉冲的能量密度为1.2J/cm ^2，激光照射次数为1000次时，由曲线拟合估计的表面Al浓度分别为9.0 × 10 ~（-3）、4.5 × 10 ~（-3）和2.7 × 10 ~（-3）Al/cm ^3。研究证实，通过TMA/H_2气体压力、激光能量密度和激光照射次数等三个参数可以控制铝的深度分布。(b)在<115>TMA/H_2、100 Torr、发射次数、8000和1.2J/cm ~ 2的条件下，在未掺杂的n型6 H-SiC（2.5 × 10 ~（-1）N/cm ~ 3）上制备了薄pn结二极管。在P型掺杂层上采用薄的Al/Ti欧姆接触，在330 nm波长处获得最大外量子效率41%的光响应。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