Chloride Vapor phase Epitaxial Growth of CuGaS_2

(1)氯化物气相外延生长CuGaS_2。原料为一氯化铜(CuCI)、三氯化镓(GaCl3)和硫(S)。源在水平四区电阻炉中加热，用氮气载气输送，并在生长区混合。衬底采用的是GaAs(100)晶片。生长过程如下。将源材料和衬底放置在生长管中各自的区域，并用N_2载气吹扫系统。之后，将载气流量降至正常流量的十分之一(氯化物为i I/min，硫化物为0.1i/min)，直到所有区域达到所需温度。在外延生长开始前的升温阶段降低流量是防止双取向生长的有效措施。在外延生长时，所有的炉子都被关闭，载气流量再次降低到十分之一…更多的是正常利率。同时，将衬底从生长区移至低温(&lt；200ﾟC)区。流量的降低和底物的去除有效地防止了多晶蛋白物质在降温过程中落在生长层上。典型的源温度为CuCl4 5 0ﾟC，GaCl3=70ﾟC，S=1 60ﾟC，有效输运速率分别为2×10~(-6)、3×10~(-6)~(-6)和8×10~(-7)~(-7)ﾟ/m in。镓、硫和一氯化铜的分子束从克努森电池中提供，在充满氢气的生长室中，压力为1×10；-4；托。源温度为T&lt；CuCL&gt；=220ﾟC；T&lt；Ga&gt；=850ﾟC和T_S=55ﾟC。在600ﾟC下生长的薄膜有很强的CaGaS_2反射X射线衍射峰。晶胞参数c为10.43A，小于大块晶体的晶胞参数c(10.48A)。这是由于CuGaS_2和GaAs的热膨胀系数不同造成的。较少

(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