本論文主要研究內容在於磷化銦/銻砷化銦鎵/砷化銦鎵(InP/InxGa1-xAs1-ySby/In0.53Ga0.47As)雙異質接面雙極性電晶體直流特性與基極材料的分析。在材料分析方面，運用固態源分子束磊晶法(solid-source molecular beam epitaxy)成長不同銻元素莫耳濃度之銻砷化銦鎵塊材於磷化銦基板上，並利用高解析度X-光繞射儀、光激發光譜儀、霍爾效應(Hall)等量測儀器分析此四元材料特性，探討銻砷化銦鎵作為異質接面雙極性電晶體之基極材料時，對其直流特性的影響。 以InP/In0.37Ga0.63As0.88Sb0.12/In0.53Ga0.47As雙異質接面雙極性電晶體為例，其元件的順向導通電壓為0.35 V相較於InP/In0.53Ga0.47As單異質接面雙極性電晶體之 0.5 V有較低的順向導通電壓。由Gummel plot之變溫量測結果所得到電晶體的能帶結構以及藉由分析銻砷化銦鎵塊材內部之應變勢能(Strain)可知，此低順向導通電壓特性係來自於In0.37Ga0.63As0.88Sb0.12之基極能隙(0.635 eV)較砷化銦鎵的能隙(0.75 eV)窄，且其射極/基極接面之導電帶不連續(0.13 eV)亦較原0.25 eV為小。此射極/基極接面結構亦改善了元件之電流增益，特別在於低電流區域。此研究顯示此新型之雙異質接面雙極性電晶體極適合低功率與高速電路之應用。 This thesis reports the characterization of InxGa1-xAs1-ySby epilayers and InP/InxGa1-xAs1-ySby/InGaAs double heterojunction bipolar transistors (DHBTs) grown on InP by solid-source molecular beam Epitaxy. InxGa1-xAs1-ySby bulk layers of difference Sb content are prepared and characterized by high resolution X-ray diffraction, photoluminescence and Hall measurements so as to examine their electronic, electrical as well as structural properties. As to the InP/In0.37Ga0.63As0.88Sb0.12/In0.53Ga0.47As DHBTs, low forward turn-on voltages as low as 0.35 V are obtained. Such a low turn-on voltage is much lower than the 0.5 V for conventional InP/In0.53Ga0.47As HBTs. Through temperature-dependent Gummel plots, photoluminescence and x-ray diffraction, the reduced turn-on voltage is attributed to the small energy band gap of InxGa1-xAs1-ySby base, the reduced conduction band offset of emitter/base junction and the residual tensile strain in the base. In addition, the current gain is also improved by the resultant emitter/base type-I band line-up, especially at the low current region. The work shows the great potential of InxGa1-xAs1-ySby DHBTs for low-power, high-speed circuit applications.
