In_(0.5)(Ga_(1-x)Al_x)_(0.5)P合金的掺杂生长特性

Growth Properties of DopedIn_(0.5)(Ga_(1-x)Al_x)_(0.5)P Alloys

利用LP MOCVD分别生长Zn和Si掺杂的In0 5(Ga1-xAlx) 0 5P外延层 ,研究生长温度、掺杂源流量、Ⅴ/Ⅲ比、Al组分以及衬底晶向偏离等生长条件对外延层掺杂浓度的影响。实验结果表明 :降低生长温度和Al含量、增加DEZn流量、选择由 (10 0 )向 (111)A偏 6～ 15°的衬底都有利于增加InGaAlP合金中Zn的掺杂浓度 ;提高生长温度和增加SiH4流量、减小Al含量和Ⅴ/Ⅲ比 ,都有助于增加Si掺杂浓度 。

The In 0 5 (Ga 1- x Al x ) 0 5 P quaternary alloys has been an interesting material,because of high recombination probability,high emission efficiency, direct band gap transition and small lattice mismatch to GaAs substrate.Thus In 0 5 (Ga 1- x Al x ) 0 5 P alloys was ideal active and cladding layer material for LEDs and LDs operating in the red to green region of the visible spectrum. However,many problems plague the MOCVD growth of In 0 5 (Ga 1- x Al x ) 0 5 P,including oxygen and carbon contamination,due to the Al,the difficulties increases as the band gap energy increases. The In 0 5 (Ga 1- x Al x ) 0 5 P materials were grown on the silicon doped GaAs substrate by LP MOCVD.The metalorganic precursors were trimethylindium(TMIn),trimethylgallium(TMGa),trimethyaluminum(TMAl).The hydride source was phosphine(PH\-3).The dopant source was silane(SiH\-4) and dimethylzinc(DEZn),respectively.Al composition in In 0 5 (Ga 1- x Al x ) 0 5 P epilayer was x =0 6. To investigate the effect of the growth conditions such as temperature,dopant flow rate,Ⅴ/Ⅲ ratio,Al composion and substrate orientations on doped concentration,the growth of doped InGaAlP alloys was studied by LP MOCVD.We demonstrated that lowering temperature and reducing Al composion,increasing the flow rate of DEZn,and selecting the substrate inclining 6 to 15° from <100> to <111> are contribute to the increasing of Zn doped concentration in InGaAlP alloys. While raising temperature and increasing the flow rate of SiH\-4,reducing Al composion and Ⅴ/Ⅲ ratio are contribute to Si doped concentration,and the orientations of substrate has no effect on the latter.