磷化銦相較傳統矽或砷化鎵材料擁有較高的電子遷移速度與崩潰電場，因此磷化銦材料系統被廣泛應用於高速異質接面雙極性電晶體上。其中銻相關材料如銻砷化鎵與銻砷化銦鎵為基極之異質接面雙極性電晶體。由於type-II之基-集極接面具有高電流傳輸能力與高截止頻率等優點，因此近年來備受關注。然而其可靠度問題至今仍未被廣泛研究，因此本論文為高濃度鈹摻雜的銻砷化銦鎵基極元件之電流壓力測試實驗，觀察元件在高電流密度操作後之特性表現。 吾人使用分子束磊晶法成長晶格匹配之銻砷化銦鎵基極雙異質接面雙極性電晶體於磷化銦基板，再使用1×10 ?m2射極尺寸製程製作之。測試條件設定元件操作於集極電流密度150與300 kA/cm2，為了加快元件衰化速度，此電流壓力測試實驗分別在環境溫度100、150、200 ℃下進行，而元件之特性都在室溫下進行量測。 由實驗結果發現Gummel圖中集極電流平行向高電壓區橫移，顯然導通電壓已增加。然而此陡接面之砷化銦鋁/銻砷化銦鎵雙異質接面雙極性電晶體與傳統使用超晶格射-基極結構之砷化銦鋁/砷化銦鎵單異質接面雙極性電晶體相比，在同樣的實驗條件下其導通電壓上升速度較為緩慢。由於其集極電流理想因子並沒有明顯改變，證明鈹擴散現象在此銻砷化銦基極材料中不明顯。 本研究也發現在1 A/cm2下萃取之導通電壓與射極電阻有同樣的上升趨勢，判斷可能是高電流密度操作造成射極歐姆接觸缺陷增加或者金屬擴散至材料內部。所以未來於更高電流密度操作時必須考慮使用高熔點的射極金屬。 InP-based heterojunction bipolar transistors (HBTs) with antimonide (Sb) content in the base, such as GaAsSb and InGaAsSb, have received a great deal of attention because of their excellent dc and microwave performance associated with type-II band alignment at the base/collector (B/C) junction. However, the reliability issues associated with the Sb-containing base have not been well studied to date. In this work, the effects of current stress on the electrical characteristics of HBTs with a highly beryllium (Be)-doped InGaAsSb base were investigated. Devices with an emitter size of 1×10 ?m2 were fabricated by a triple mesa wet-etching process. The stress current density used in this work was either 150 or 300 kA/cm2. To accelerate device degradation, current stress was performed at a junction temperature of 200 and 250 ℃. The collector currents for all the InGaAsSb base HBTs show parallel shifts toward higher base/emitter voltage after the stress. The unchanged collector ideality factors and junction capacitances imply that there were no Be out-diffusion at the junctions, thereby indicating the strength of InGaAsSb base HBTs for higher current density operations.
