砷化銦/銻化鋁金屬-氧化物-半導體高電子遷移率電晶體之發展; Development of InAs/AlSb Metal-Oxide-Semiconductor HEMT

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Title:	砷化銦/銻化鋁金屬-氧化物-半導體高電子遷移率電晶體之發展;Development of InAs/AlSb Metal-Oxide-Semiconductor HEMT
Authors:	范大偉;Da-Wei Fan
Contributors:	電機工程研究所
Keywords:	砷化銦/銻化鋁;金屬-氧化物-半導體高電子遷移率電晶體;InAs/AlSb;Metal-Oxide-Semiconductor HEMT
Date:	2009-07-03
Issue Date:	2009-09-22 12:15:53 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	砷化銦/銻化鋁高電子遷移率電晶體非常適合應用於低功率、高速之電子元件。也因其材料系統的能帶為第二型能帶對齊方式且為低能隙造成二個嚴重的缺點，一個為在高閘極偏壓時會產生電洞穿遂效應。一個為在高電場下會發生衝擊離化所產生的電洞無法侷限於導通層中造成漏電流增加。因此置入一高介電係數薄膜在閘極之下以期降低漏電流。我們先對氧化鋁薄膜進行物性及電性分析，物性包括有厚度鑑定、組成成份、表面粗糙度及熱穩定性。電性包括有不同基板的電容-電壓量測、漏電流與崩潰電場量測。此外我們將氧化鋁薄膜置入傳統的砷化銦/銻化鋁高電子遷移率電晶體磊晶層上製作出砷化銦/銻化鋁金屬-氧化物-高電子遷移率電晶體。在閘極長度為2μm的元件上汲極電流可達286 mA/mm，轉導可達495mS/mm在汲極偏壓為0.4V時，次臨界斜率可達416(mV/dec)，介面捕獲電荷密度可達1~2 1011eV-1cm-2，漏電流比傳統HEMT降低2~3個數量級且有良好的高頻特性ft，fMAX分別為10.1 GHz，19.1GHz在汲極偏壓為0.5 V時，閘極偏壓為-2.6 V時。 InAs/AlSb high electron mobility transistor has great promise in high speed and low power applications. However, two drawbacks observed in the devices are closely associated with type II band line-up and small bandgap InAs channel. One is band-to-band hole tunneling; another is serious carrier impact ionization. Generated holes cannot be confined in the channel and result in serious kink and gate currents. In the thesis, we deposit a high-k Al2O3 dielectric under the gate to alleviate the gate leakage. We first analyzed electrical and physical properties of the Al2O3 thin film. The physical properties include thin film thickness, composition, surface roughness and thermal stability. The electrical properties include C-V measurement, I-V measurement and J-E measurement. Different substrates are chosen for these characterizations. Based on the developed high-k mdielectric, we fabricated InAs/AlSb MOS-HEMTs using the conventional InAs/AlSb HEMT epitaxy materials. In a device with 2.0?m gate length, maximum drain current is 286mA/mm and peak transconductance is 495mS/mm at drain voltage of 0.4V. The subthreshold slope is 416mV/dec. The interface trap density is 1~2 1011 eV-1cm-2. The gate leakage current was suppressed at least 2~3 order compared with conventional HEMT. An fT of 10.1 GHz and an fmax of 19.9 GHz are obtained respectively at VDS = 0.5 V and VGS = - 2.6V.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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