在本論文中,我們利用固體源分子束磊晶法(SSMBE)成長兩種矽鍺通道摻雜場效電晶體,一種是均勻通道摻雜場效電晶體,另一種是漸變矽鍺通道均勻摻雜場效電晶體.採用的摻雜源為硼元素.在磊晶薄膜分析方面,我們以二次離子質譜儀來探討硼摻雜層的濃度和各層接面與縱深分佈.

　　在實驗方面,這兩種矽鍺異質結構場效電晶體都已成功研製出來,其中漸變矽鍺通道均勻摻雜場效電晶體的特性尤其出色,因為漸變通道會場生一個內建電場,有效的侷限載子在矽鍺通道中,此舉能大大改善元件的特性,其最高互導值為14.2 mS/mm, 而最大汲極電流可達65 mA/mm.

　　在另一方面,由於金半場效電晶體的操作電壓範圍受到蕭特基接面特性的限制,所以無法承受過大的閘極電壓.因此,在金屬和半導體之間加入了氧化層可有效的解決這個問題.使用直接光激化學氣相沉積法成長的二氧化矽層，其物理特性非常接近於一般用熱氧化法成長的二氧化矽層，且其電特性在元件的應用上也是可被接受的。而直接光激化學氣相沉積法的優點在於能夠有效的把氘燈(D2)產生的能量直接轉移給反應氣體而不產生熱能。又因為光激化學氣相沉積法的氧化層是在低溫下沉積(<1000℃)，因此熱鬆弛也能因而降到最低。
本論文中，我們利用和金半場效電晶體相同的結構去研製出矽鍺異質結構金氧半場效電晶體,而從實驗結果我們得到不錯的電流電壓特性,以及較大的閘極電壓操作範圍。

　　In this these, two p-type SiGe doped-channel field-effect transistors with different Ge profile were grown by solid-source molecular beam epitaxy (SSMBE). Secondary ion mass spectrum (SIMS) was used to verify the Ge profile in Si1-xGex channel.

　　Then, the SiGe-based MESFETs with a uniform Ge channel and with a Ge graded-channel were successfully fabricated. The graded variation of the Ge fraction in channel induced built-in field can prevent transconductance from shaping down drastically under forward gate bias and increase the carrier confinement for device operation. It is found that by grading Ge fraction in the channel, the devices exhibit the excellent property not only of higher current density (65 mA/mm) but also enhancement in extrinsic transconductance (14.2 mS/mm) and linear operation range over a wider dynamic range than those of devices with uniform Ge profile for the same integrated Ge dose in SiGe conducting well.

　　In addition, MESFETs suffer from a reduced gate voltage swing due to the onset of a significant leakage current across the Schottky gate under forward bias condition. SiGe/Si metal-oxide-semiconductor heterojunction field effect transistors (MOSHFETs) are fabricated with photo-CVD oxide as the insulating layer and compared with SiGe/Si heterostructure MESFETs with similar structure. Photo-CVD oxide is a good candidate for gate dielectrics in SiGe MOSFETs because its low processing temperature can avoid the relaxation of strained SiGe layers and segregation of Ge atoms. From the experimental results, SiGe MOSHFETs with different Ge profile show good FET characteristics.

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