Chloride Vapor phase Epitaxial Growth of CuGaS_2

(1)氯化物气相外延生长CuGaS_2源材料为CuCl、GaCl_3和S。源在水平四区电阻炉中加热，并由氮气载气输送并在生长区混合。GaAs（100）晶片用作衬底。生长过程如下。将源材料和衬底分别放置在生长管中的相应区域，用N_2载气吹扫系统。之后，将载气流速降低至正常流速的十分之一（氯化物为11/min，硫酸盐为0.11/min），直至所有区域达到所需温度。发现在外延生长开始之前的加热期间的流速降低对于防止双取向生长是有效的。在外延生长开始时，关闭所有的炉，并再次将载气流速降低到十分之一 ...更多信息 正常利率。同时，将衬底从生长区移动到低温（<200 ° C）区。流速的降低和衬底的去除是有效的，以防止多晶材料落在生长层在冷却期间。典型的源温度为CuCl=450 ℃、GaCl_3=70 ℃和S=160 ℃。有效转运速率分别为2 × 10 ~（-4）<-6>、3 × 10 ~（-4）<-6>和8 × 10 <-7>~（-4）mol/min。(2)用氯化物分子束外延法在GaAs（100）衬底上生长了CuGaS_2CuGaS_2薄膜。镓、硫和一氯化铜的分子束由填充有氢气的生长室中的Knudsen电池供应，压力为1 × 104<-4>托。源温度为T_<cucl>=220 ℃、T_<Ga>=850 ℃和T_s=55 ℃。在600 ℃下生长的CaGaS_2薄膜在X射线衍射中有一个强的CaGaS_2（004）反射峰。晶格常数c为10.43A，小于块体晶体的晶格常数c（10.48A）。这是由于CuGaS_2和GaAs的热膨胀系数不同造成的。少

(1) Chloride vapor phase epitaxial growth of CuGaS_2The source materials wore copper monochloride (CuCI), gallium trichloride (GaCl_3) and sulfur (S). The sources were heated in a horizontal four-zone resistance furnace, and transported by a nitrogen carrier gas and mixed in the growth region. GaAs (100) wafers were used for substrates. The growth procedure was as follows. The source materials and substrate wee set at the respective zone in the growth tube, and the system was purged with the N_2 carrier gas. After that, the carrier gas flow rates were reduced to one tenth of the normal flow rates (I I/min for chlorides and 0.1 I/min for sulter) until all the zones reached the required temperatures. The flow rate reduction during the heating-up period before the beginning of the epitaxial growth was found to be effective to prevent doubly oriented growth. At the en ([of the epitaxial growth, all the furnaces were turned off and the carrier gas flow rates were reduced again to one tenth … More of the normal rates. At the same time, the substrates were moved from the growth zone to a low temperature (<200ﾟC) zone. The flow rate reduction and the substrates removal were effective to prevent polycrystallin materials falling on the grown layer during the cooling period. Typical source temperatures were CuCl=450ﾟC, GaCl_3=70ﾟC and S=160ﾟC. The effective transport rates were 2x1O^<-6> , 3x1O^<-6> and 8xlO^<-7> mol/min, respectively.(2) Very low pressure epitaxial growth of CuGaS_2CuGaS_2 films were grown on GaAs (100) substrates by chloride MBE method. Molecular beams of gallium, sulfur and copper monochloride were supplied from Knudsen cells in a growth chamber filled with hydrogen gas with a pressure of 1x10^<-4> Torr. Source temperatures were T_<cucl>=220ﾟC, T_<Ga>=850ﾟC and T_s=55ﾟC. Films grown at 600ﾟC showed a strong X-ray diffraction peak of CaGaS_2 (004) reflection. The lattice parameter c was 10.43A and smaller than that of bulk crystals (10.48A). The difference is due to the difference in thermal expansion coefficient between CuGaS_2 and GaAs. Less