In this paper, in order to solve the interface-trap issue and enhance the transconductance induced by high-k dielectric in metal-insulator-semiconductor （MIS） high electron mobility transistors （HEMTs）, we demonst...In this paper, in order to solve the interface-trap issue and enhance the transconductance induced by high-k dielectric in metal-insulator-semiconductor （MIS） high electron mobility transistors （HEMTs）, we demonstrate better performances of recessed-gate A1203 MIS-HEMTs which are fabricated by Fluorine-based Si3N4 etching and chlorine- based A1CaN etching with three etching times （15 s, 17 s and 19 s）. The gate leakage current of MIS-HEMT is about three orders of magnitude lower than that of A1GaN/CaN HEMT. Through the recessed-gate etching, the transconductanee increases effectively. When the recessed-gate depth is 1.02 nm, the best interface performance with Tit----（0.20--1.59） p^s and Dit ：（0.55-1.08）x 1012 cm-2.eV- 1 can be obtained. After chlorine-based etching, the interface trap density reduces considerably without generating any new type of trap. The accumulated chlorine ions and the N vacancies in the AIGaN surface caused by the plasma etching can degrade the breakdown and the high frequency performances of devices. By comparing the characteristics of recessed-gate MIS-HEMTs with different etching times, it is found that a low power chlorine-based plasma etching for a short time （15 s in this paper） can enhance the performances of MIS-HEMTs effectively.展开更多
The Three Gorges Project has always been under global spotlight, even when it was still being conceived in the 1980s. No wonder. The project, scheduled for completion by 2010, will be the greatest hydroelectric projec...The Three Gorges Project has always been under global spotlight, even when it was still being conceived in the 1980s. No wonder. The project, scheduled for completion by 2010, will be the greatest hydroelectric project ever built by the human race. Moreover, some 1.2 million people are being resettled in the course of its construction, the largest human exodus caused by any construction project ever undertaken in the world.展开更多
目的:检测先天性双侧输精管缺如(congenital bilateral absence of the vas deferens,CBAVD)患者中囊性纤维化跨膜转导调节因子(cystic fibrosis transmembrane conductance regulator,CFTR)基因和CBAVD易感基因的突变情况,探讨它们与CB...目的:检测先天性双侧输精管缺如(congenital bilateral absence of the vas deferens,CBAVD)患者中囊性纤维化跨膜转导调节因子(cystic fibrosis transmembrane conductance regulator,CFTR)基因和CBAVD易感基因的突变情况,探讨它们与CBAVD发病风险的相关性。方法:对13例诊断为孤立发生的CBAVD患者的致病基因CFTR及易感基因黏附型G蛋白偶联受体G2(adhesion G protein-coupled receptor G2,ADGRG2)、上皮细胞钠离子通道β亚单位(sodium channel epithelial 1 subunit beta,SCNN1B)和碳酸酐酶12(carbonic anhydrase,CA12)和溶质载体家族9成员3(solute carrier family 9 member A3,SLC9A3)行全外显子测序及Sanger测序验证,针对CFTR基因多态性位点、内含子及侧翼序列行聚合酶链式反应(polymerase chain reaction,PCR)扩增后用Sanger测序,并运用生物信息学方法对CBAVD易感基因新发突变进行保守性分析和有害性预测。对13例CBAVD患者中1例患者的家系进行遗传学分析,评估子代遗传风险。结果:外显子测序发现13例CBAVD患者中,只有6例患者检测到CFTR基因外显子突变,有6种错义突变:c.2684G>A(p.Ser895Asn)、c.4056G>C(p.Gln1352His)、c.2812G>T(p.Val938Leu)、c.3068T>G(p.Ile1023Arg)、c.374T>C(p.Ile125Thr)、c.1666A>G(p.Ile556Val),1种无义突变:c.1657C>T(p.Arg553Ter),这6例患者中有2例患者同时还存在CFTR的纯合p.V470位点,另外7例患者未检测出CFTR基因外显子区域的突变。13例CBAVD患者中,3例患者携带纯合p.V470的多态性位点,4例患者携带5T等位基因,2例患者携带TG13等位基因,10例患者携带c.-966T>G位点。4例CBAVD患者同时携带以上CFTR基因突变位点中的2~3个位点。13例患者中CBAVD易感基因突变情况:1种ADGRG2错义突变c.2312A>G(p.Asn771Ser),2种SLC9A3错义突变c.2395T>C(p.Cys799Arg)、c.493G>A(p.Val165Ile),1种SCNN1B错义突变c.1514G>A(p.Arg505His)和1种CA12错义突变c.1061C>T(p.Ala354Val),其中,SLC9A3基因的c.493G>A(p.Val165Ile)突变位点是首次在CBAVD患者中被发现,以上5种突变位点在gnomAD数据库中的人群变异频率极低,属于罕见突变,用Mutation Taster和Polyphen-2软件预测显示SLC9A3基因的c.493G>A(p.Val165Ile)位点和SCNN1B基因的c.1514G>A(p.Arg505His)位点的有害性等级为致病突变。1例家系遗传分析发现,先证者的c.1657C>T(p.Arg553Ter)突变为新生突变,先证者父亲、母亲均未携带该突变,先证者及其配偶通过辅助生殖技术孕育1女婴,该女婴遗传了先证者的致病性突变c.1657C>T(p.Arg553Ter)。结论:CFTR基因突变仍然是中国CBAVD患者的主要致病原因,但突变的分布与频率与国内外其他研究的数据存在一定差异,需要进一步扩充中国CBAVD患者的CFTR突变谱;ADGRG2、SLC9A3、SCNN1B和CA12易感基因可能解释部分无CFTR突变的CBAVD病例;CBAVD患者多无特殊临床表现,建议临床医生确诊前对患者行进一步的体格检查,并结合其阴囊超声或经直肠超声检查;建议将CFTR基因突变检测应用于辅助生殖前的遗传学筛查,降低子代罹患CBAVD及囊性纤维化的风险。展开更多
基金supported by the National Key Science and Technology Special Project,China (Grant No. 2008ZX01002-002)the National Natural Science Foundation of China (Grant No. 60736033)
文摘In this paper, in order to solve the interface-trap issue and enhance the transconductance induced by high-k dielectric in metal-insulator-semiconductor （MIS） high electron mobility transistors （HEMTs）, we demonstrate better performances of recessed-gate A1203 MIS-HEMTs which are fabricated by Fluorine-based Si3N4 etching and chlorine- based A1CaN etching with three etching times （15 s, 17 s and 19 s）. The gate leakage current of MIS-HEMT is about three orders of magnitude lower than that of A1GaN/CaN HEMT. Through the recessed-gate etching, the transconductanee increases effectively. When the recessed-gate depth is 1.02 nm, the best interface performance with Tit----（0.20--1.59） p^s and Dit ：（0.55-1.08）x 1012 cm-2.eV- 1 can be obtained. After chlorine-based etching, the interface trap density reduces considerably without generating any new type of trap. The accumulated chlorine ions and the N vacancies in the AIGaN surface caused by the plasma etching can degrade the breakdown and the high frequency performances of devices. By comparing the characteristics of recessed-gate MIS-HEMTs with different etching times, it is found that a low power chlorine-based plasma etching for a short time （15 s in this paper） can enhance the performances of MIS-HEMTs effectively.
文摘The Three Gorges Project has always been under global spotlight, even when it was still being conceived in the 1980s. No wonder. The project, scheduled for completion by 2010, will be the greatest hydroelectric project ever built by the human race. Moreover, some 1.2 million people are being resettled in the course of its construction, the largest human exodus caused by any construction project ever undertaken in the world.
文摘目的:检测先天性双侧输精管缺如(congenital bilateral absence of the vas deferens,CBAVD)患者中囊性纤维化跨膜转导调节因子(cystic fibrosis transmembrane conductance regulator,CFTR)基因和CBAVD易感基因的突变情况,探讨它们与CBAVD发病风险的相关性。方法:对13例诊断为孤立发生的CBAVD患者的致病基因CFTR及易感基因黏附型G蛋白偶联受体G2(adhesion G protein-coupled receptor G2,ADGRG2)、上皮细胞钠离子通道β亚单位(sodium channel epithelial 1 subunit beta,SCNN1B)和碳酸酐酶12(carbonic anhydrase,CA12)和溶质载体家族9成员3(solute carrier family 9 member A3,SLC9A3)行全外显子测序及Sanger测序验证,针对CFTR基因多态性位点、内含子及侧翼序列行聚合酶链式反应(polymerase chain reaction,PCR)扩增后用Sanger测序,并运用生物信息学方法对CBAVD易感基因新发突变进行保守性分析和有害性预测。对13例CBAVD患者中1例患者的家系进行遗传学分析,评估子代遗传风险。结果:外显子测序发现13例CBAVD患者中,只有6例患者检测到CFTR基因外显子突变,有6种错义突变:c.2684G>A(p.Ser895Asn)、c.4056G>C(p.Gln1352His)、c.2812G>T(p.Val938Leu)、c.3068T>G(p.Ile1023Arg)、c.374T>C(p.Ile125Thr)、c.1666A>G(p.Ile556Val),1种无义突变:c.1657C>T(p.Arg553Ter),这6例患者中有2例患者同时还存在CFTR的纯合p.V470位点,另外7例患者未检测出CFTR基因外显子区域的突变。13例CBAVD患者中,3例患者携带纯合p.V470的多态性位点,4例患者携带5T等位基因,2例患者携带TG13等位基因,10例患者携带c.-966T>G位点。4例CBAVD患者同时携带以上CFTR基因突变位点中的2~3个位点。13例患者中CBAVD易感基因突变情况:1种ADGRG2错义突变c.2312A>G(p.Asn771Ser),2种SLC9A3错义突变c.2395T>C(p.Cys799Arg)、c.493G>A(p.Val165Ile),1种SCNN1B错义突变c.1514G>A(p.Arg505His)和1种CA12错义突变c.1061C>T(p.Ala354Val),其中,SLC9A3基因的c.493G>A(p.Val165Ile)突变位点是首次在CBAVD患者中被发现,以上5种突变位点在gnomAD数据库中的人群变异频率极低,属于罕见突变,用Mutation Taster和Polyphen-2软件预测显示SLC9A3基因的c.493G>A(p.Val165Ile)位点和SCNN1B基因的c.1514G>A(p.Arg505His)位点的有害性等级为致病突变。1例家系遗传分析发现,先证者的c.1657C>T(p.Arg553Ter)突变为新生突变,先证者父亲、母亲均未携带该突变,先证者及其配偶通过辅助生殖技术孕育1女婴,该女婴遗传了先证者的致病性突变c.1657C>T(p.Arg553Ter)。结论:CFTR基因突变仍然是中国CBAVD患者的主要致病原因,但突变的分布与频率与国内外其他研究的数据存在一定差异,需要进一步扩充中国CBAVD患者的CFTR突变谱;ADGRG2、SLC9A3、SCNN1B和CA12易感基因可能解释部分无CFTR突变的CBAVD病例;CBAVD患者多无特殊临床表现,建议临床医生确诊前对患者行进一步的体格检查,并结合其阴囊超声或经直肠超声检查;建议将CFTR基因突变检测应用于辅助生殖前的遗传学筛查,降低子代罹患CBAVD及囊性纤维化的风险。
