砷離子佈植砷化鎵薄膜在不同退火條件下其材料結構與電性分析

Abstract

本篇論文主要是以穿透式電子顯微鏡、雙晶X-ray、冷激光及電流- 電壓特性量測實驗來探討砷離子佈植在n+型及半絕緣性砷化鎵基材中，改 變退火的溫度及時間，觀察在佈植層中材料結構及電性的變化。在穿透式 電子顯微鏡實驗中，發現在n+型砷化鎵中砷析出物的形成與退火的溫度及 佈植的劑量有密切的關係。在高斯分佈峰值處(晶片表面下900A)，砷析出 物峰值濃度在砷離子佈植劑量為10^14，10^15，10^16 cm-2 時，分別約 為~2e17，5e17，4e18cm-3，對應的半徑大小約為10A，35A，50A。而在砷 離子佈植劑量為10^16 cm-2，退火溫度為500C及600C時，砷析出物的濃度 分別約為~2e16cm-3及1e17cm-3，退火溫度為400C時則未發現有砷析出物 形成。而在半絕緣性砷化鎵中，可籍由薄膜內差排及表面晶粒的變化觀察 到退火處理後的再結晶現象。在雙晶x-ray量測實驗中，同樣地觀察的到 在n+型及半絕緣性砷化鎵中，除了有能隙間躍遷的譜線之外，另有波長 為840-860nm的輻射。此波長的譜線與SiGa+能階至SiAs-能階及矽的複合 缺陷能階至SiAs-能階的躍遷有關。在電流-電壓特性量測實驗中，發現在 退火處理後的砷離子佈植砷化鎵薄膜中，砷析出物的濃度與薄膜的電阻並 無太直接的關係。 The structural and electrical properties of the arsenic-ion- implanted GaAs under different annealing conditions were studied by using transmission electron microscope (TEM), double crystal x-ray diffraction , photoluminescene (PL) and current-voltage (I-V) characteristics measurement techniques. TEM has used to study the formation of arsenic precipitates and recrystallization both in n+-type and semi-insulating implanted films in addition to the structural defects. The peak concentrations of arsenic precipitates in n+-type implanted GaAs films are also estimated to be ~2e17cm-3,5e17cm-3,and 4e18cm-3 while the films are implanted with dosage of 10^14, 10^15, and 10^16 cm-2 respectively. And the corresponding size of arsenic precipitates are 10A, 30A, and 50A separately. The donor-to- acceptor transitions from SiGa+ or Si clusters to SiAs- were observed by emitted lines of 840-860nm from PL experiment. The high resistivity property in the annealing arsenic-ion-implanted GaAs film seems to bear no relation to the concentration of arsenic precipitates by characteristic measurements ofcurrent- voltage.