高速電子遷移率電晶體的設計概念在1978年被提出，進一步的在1980年利用砷化鋁鎵/砷化鎵 (AlGaAs/GaAs)化合物半導體成功實現此設計概念。隨著磊晶和製程技術的發展，銻化物半導體已被證明具有比砷化鎵半導體更快的電子與電洞遷移率且更低的操作偏壓，極有潛力成為下一代高頻低功率放大器的主力。本論文內容概括銻化物化合物半導體從磊晶成長到元件製作的實驗發展與成果。 因為缺乏與銻化物晶格常數匹配且絕緣性良好又便宜的基板，我們利用變晶式(metamorphic)分子束磊晶成長技術，成長銻化鋁鎵(AlxGa1-xSb)緩衝層於砷化鎵基板上。因為晶格常數的不匹配，大量的缺陷將從基板與緩衝層的介面產生，因此發展高品質、低缺陷密度的緩衝層，為首要目標。在成功發展緩衝層於砷化鎵基板後，本研究主要分成兩種量子井結構，其一為砷化銦/銻化鋁(InAs/AlSb)，主要發展高電子遷移率電晶體，電子遷移率超過25,000 cm2/V-s;其二為銻化銦鎵/銻化鋁(InGaSb/AlSb)，主要發展高電洞遷移率電晶體，電洞遷移率超過1200 cm2/V-s，以上實驗結果皆位於世界的領先地位。本研究團隊並成功地證明整合兩種量子井的結構成長於單一砷化鎵基板的技術，和世界上第一次展示的單石整合砷化銦/銻化鋁與銻化銦鎵/銻化鋁元件特性。 在元件製程發展初期，利用大線寬(2 μm)的光學微影閘極元件調整製程參數與確認磊晶品質。接著導入電子束微影閘極(0.25 μm)，提升元件高頻特性。砷化銦/銻化鋁(InAs/AlSb)高電子遷移率電晶體呈現截止頻率(ft)高達105 GHz，銻化銦鎵/銻化鋁(InGaSb/AlSb)高電洞遷移率電晶體呈現截止頻率(ft)高達15 GHz，皆達到世界級的水準。除了展現元件高頻特性之外，研究還包括了藉由觀察不同儲存時期砷化銦/銻化鋁(InAs/AlSb)元件的特性，分析磊晶氧化與元件特性的相關性;緩衝層磊晶品質對於銻化銦鎵/銻化鋁(InGaSb/AlSb)元件特性的影響。The development of high electron mobility transistors (HEMTs) started in 1978. Modulation-doped AlGaAs/GaAs heterostructures were immediately demonstrated and revealed the formation of two-dimentional electron gas (2DEG) with enhanced electron mobility. As epitaxy and fabrication technology developed, the advantages of Sb-based devices over conventional GaAs- or InP-based devices are the attainment of high-frequency operation with much lower power consumption. This thesis includes the Sb-based semiconductor developments and results from epitaxial growth to device fabrication. Metamorphic AlxGa1-xSb buffer layers were grown on semi-insulating GaAs substrate and accommodated a large number of defects from the lattice mismatch interface. Two quantum well structures were grown on the developed buffer layer. One is InAs/AlSb heterostructure, which has electron mobility over 25,000 cm2/V-s and is applied for n-channel HFET. The other is InGaSb/AlSb heterostructure, which has hole mobility over 1200 cm2/V-s and is applied for p-channel HFET. In additions, we successfully developed the growth technology of monolithic n- and p-channel epitaxy on the same GaAs wafer and first demonstrated the characteristics of n- and p-channel HFETs. In the beginning of the fabrication process, large gate-length devices (2 μm) were used to check the quality of epitaxy and adjust the fabricated parameters. After that, e-beam gate devices (0.25 μm) were successfully demonstrated to promote the poteneials of materials. InAs/AlSb and InGaSb/AlSb HFETs exhibited cut-off frequency of 105 GHz and 15 GHz, respectively. Except characteristics of devices, two interesting topics were included. One is that we investigated the device characteristics of InAs/AlSb HFETs subjected to different periods of time storage in atmospheric ambiance after fabrication. The other is that we reported the effect of growth temperature on carrier transport and device characteristics in InGaSb/AlSb heterostructure.
