基区重掺杂的高电流增益AlGaAs/GaAs异质结双极晶体管

研究了AlGaAs/GaAs异质结双极晶体管(HBT)的电流增益和AlGaAs/GaAs异质结二极管(HD)的发光强度随偏压的变化。HBT的发射板-基极结的理想因子接近于1,这与HD中发光强度随偏压的变化关系相一致。重掺杂基区HBT电流增益的降低被认为是基区中非辐射复合电流所引起。在基区掺杂为2×10~(10)cm~(-3)的HBT中得到80的高电流增益。     

高温Al0.3Gao.22In0.48P/GaAs HBT电流增益的计算分析

建立了Al0.3Ga0 22In0.48P/GaAs异质结双极型晶极管(HBT)中电流输运过程的模型,利用实验得到的材料特性参数进行了HBT电流增益随温度变化的模拟。随着温度上升,小电流时电流增益下降较多,而大电流时电流增益基本保持不变.模拟表明,小电流下电流增益的下降主要是由eb结空间电荷区的复合电流随温度增加而造成的;而大电流下电流增益直至723K下降仍小于10％.最高工作温度可达848K.由于采用的计算方法充分考虑了空间电荷区复合电流的影响,模拟结果较为符合实际情况,可为研制高性能HBT器件所需材料提供参考依据。     

SiGe HBT 60Co γ辐照总剂量效应

测量了SiGe HBT直流增益在60Coγ辐照过程中随剂量及器件电流注入水平的变化。实验结果显示在累计辐照剂量超过5 000 Gy(Si)后,器件电流增益变化与辐照剂量存在线性反比关系,且增益损伤系数与器件电流注入水平有关;器件在受到总剂量为2.78×104Gy(Si)辐照后,器件静态基极电流Ib、集电极电流Ic、静态直流增益及最大振荡频率fmax出现不同程度退化;但器件其他电参数如截止频率fT、交流增益|H21|及结电容(CCBO)与辐照前相比未出现显著退化。利用MEDICI数值模拟分析了SiGe HBT参数退化机理。     

一种新型的Pt-NiO混合敏感膜全固态 溶解CO2传感器及其特性测量

为了方便的测量溶解二氧化碳(CO₂),利用室温下NiO对CO₂的敏感特性,基于碳糊成膜方法,研制了一种新型全固态溶解CO₂传感器.文章中,分析了传感器的结构和NiO敏感膜对CO₂的敏感机理,测量了不同工作点和不同温度下传感器输出电压ΔV_rs随着溶解CO₂浓度变化的响应特性.实验结果显示,基于MISFET结构的Pt-NiO混合敏感膜溶解CO₂传感器可以在室温下方便的检测溶解CO₂浓度.     

辐照对SiGe HBT增益的影响

比较了电子和γ射线辐照后SiGe HBT和Si BJT直流增益β的变化.在Vbe≤0.5V时,较高剂量辐照时SiGe HBT的放大倍数辐照损伤因子d(β)为负;在Vbe≥0.5V时,SiGe HBT的d(β)远比Si BJT的小.SiGe HBT有更好的抗辐照性能.针对测得的一些电子陷阱对辐照致性能变化的影响进行了讨论.     

辐照对SiGe HBT增益的影响

比较了电子和γ射线辐照后SiGe HBT和Si BJT直流增益β的变化.在Vbe≤0.5V时,较高剂量辐照时SiGe HBT的放大倍数辐照损伤因子d(β)为负;在Vbe≥0.5V时,SiGe HBT的d(β)远比Si BJT的小.SiGe HBT有更好的抗辐照性能.针对测得的一些电子陷阱对辐照致性能变化的影响进行了讨论.     

薄栅介质层可靠性与陷阱统计分析

本文以高电场(＞11.8MV/cm)恒电流TDDB为手段研究了厚度为7.6、10.3、12.5、14.5nm薄氧化层的击穿统计特性.实验分析表明在加速失效实验中测量击穿电量Q_bd的同时,还可以测量击穿时的栅电压增量ΔV_bd.因为ΔV_bd的统计分布反映了栅介质层中带电陷阱的数量及其位置分布,可以表征栅介质层的质量和均匀性.此外由Q_bd和ΔV_bd能够较合理地计算临界陷阱密度N_bd.实验结果表明本征击穿时N_bd与测试条件无关而随工艺和介质层厚度变化.同样厚度时N_bd反映不同工艺生成的介质质量.陷阱生成的随机性使N_bd随栅介质厚度减小而下降.氧化层厚度约10nm时N_bd达到氧化层分子密度的1%发生击穿(10²⁰cm^-3).N_bd的物理意义清楚,不象Q_bd随测试应力条件变化,是薄栅介质层可靠性的较好的定量指标.     

InGaP/GaAs HBT器件的制备及其特性

采用在发射区台面腐蚀时保留InGaP钝化层和去除InGaP钝化层的方法制备了两种InGaP/GaAs异质结双极晶体管(HBT)器件,研究了InGaP钝化层对HBT器件基区表面电流复合以及器件直流和射频微波特性的影响.对制备的两种器件进行了对比测试后得到:保留InGaP钝化层的HBT器件最大直流增益(β)为130,最高振荡频率(fmax)大于53 GHz,功率附加效率达到61％,线性功率增益为23 dB;而去除InGaP钝化层的器件最大β为50,fnax大于43 GHz,功率附加效率为57％,线性功率增益为18 dB.测试结果表明,InGaP钝化层作为一种耗尽型的钝化层能有效抑制基区表面电流的复合,提高器件直流增益,改善器件的射频微波特性.     

Al_xGa_(0.52-x)In_(0.48)P/GaAs异质结双极晶体管高温特性的计算分析

建立了适用于缓变 Alx Ga0 .5 2 -x In0 .48P/Ga As HBT的解析模型。考虑了 Al组分 x的变化对 HBT温度特性的影响。分析结果表明 ,在实用的电流范围 (Jc在 1 0 3 A/cm2 左右 )内 ,Alx Ga0 .5 2 -xIn0 .48P/Ga As HBT随着 x的增大 ,其电流增益的稳定性也上升 ,当 x=0 .3时工作温度可超过 70 0K。文章还分析了高温时 HBT电流增益下降的原因     

In_xGa_(1-x)As/GaAs应变单量子阱结构的静压光致发光研究

在室温和液氮温度下,0-60kbar范围内对In_xGa(1-x)As/GaAs应变单量子阱结构进行了静压光致发光研究.在室温下,量子阱中发光峰随压力的变化是亚线性的,而在液氮温度下是线性的.阱中发光峰的压力系数比GaAs势垒的小约10％左右.发现对应于导带第二子带的发光峰的压力系数略大于第一子带的.此结果与GaAs/Al_xGa_(1-x)As量子阱的情况正好相反.     

InGaAs/InP微波双极型晶体管的研制

本文叙述双收集区NpnN型InGaAs/InP异质结双极型晶体管的实验结果.给出器件的击穿特性、开关特性.高频特性和温度特性.理论分析和实验结果表明,n型InGaAs第一收集区的厚度对晶体管的击穿特性和开关特性有重要影响.器件的击穿电压BV_(CE0)=20伏,贮存时间t_s=0.5ns(Ic=50mA,I_(B1)=10mA,回抽电流I_(B2)=0),f_T=1.2GHz(V_(CE)=6V,Ic=15mA).在77～433K范围内h_(fe)变化很小,在4K下h_(fe)≌1,并表现出强烈的俄立(Early)效应.     

A high-current-gain low-temperature pseudo-HBT utilizing a sidewallbase-contact structure (SICOS)

A silicon pseudo-heterojunction bipolar transistor (HBT) with a current gain of over 100 at 77 K has been successfully fabricated using the upward operation of a self-aligned sidewall base-contact structure (SICOS). The measured characteristics agree well with the theoretical prediction, showing a negative exponential temperature dependence of current gain and a 2500-times larger collector current than in the conventional transistor at 77 K. This makes homojunction bipolar transistor operation at low temperatures feasible and has the potential to overcome the bipolar/BiCMOS limitations     

Temperature dependence of the threshold current of QW lasers

The temperature dependence of the threshold current in GaInAs-based laser structures has been studied in a wide temperature range (4.2 ≤ T ≤ 290 K). It is shown that this dependence is monotonic in the entire temperature interval studied. Theoretical expressions for the threshold carrier density are derived and it is demonstrated that this density depends on temperature linearly. It is shown that the main contribution to the threshold current comes from monomolecular (Shockley-Read) recombination at low temperatures. At T > 77 K, the threshold current is determined by radiative recombination. At higher temperatures, close to room temperature, Auger recombination also makes a contribution. The threshold current grows with temperature linearly in the case of radiative recombination and in accordance with T ³ in the case of Auger recombination.     

Temperature dependence of high-frequency performance ofAlGaAs/InGaAs pseudomorphic HEMT's

High-frequency measurements of 1.5-μm gatelength AlGaAs/InGaAs pseudomorphic HEMTs have been performed at temperatures ranging from 77 to 463 K. A 28% increase and 27% decrease in f_T were observed by changing the temperature from 300 to 77 K and from 300 to 463 K, respectively. The effective saturation velocity evaluated from the total delay time, 1/2πf_T, versus reciprocal I_DS relation reveals almost the same temperature dependence as f_T. It is also shown that the temperature dependence is similar to that of calculated velocity at high electric fields but not to that at low fields. This suggests that the temperature dependence of the HEMT performance is determined by that of the saturation velocity in the channel     

A column-base InP lateral bipolar transistor

An InP lateral bipolar transistor has been successfully fabricated on a semi-insulating substrate by implanting Si⁺ as the emitter and collector contacts and Mg⁺ as the column base. An array of 33 1-μm-diameter columns with 1-μm separation between each was formed between the emitter-collector spacing of 3 μm. A current gain of 290 was obtained at 77 K; it was over 12 at room temperature     

On the low-temperature static and dynamic properties ofhigh-performance silicon bipolar transistors

In a study performed over the temperature range of 400 to 77 K, Si bipolar transistors were found to have near-ideal characteristics at low temperatures with β as high as 80 at 77 K. Detailed calculations indicate that the conventional theory of the temperature dependence of β does not match the data. The discrepancy can be removed if it is assumed that a phenomenological thermal barrier to hole injection is present. Emitter-coupled logic (ECL) ring oscillators are functional at 85 K with no degradation in speed until about 165 K when compared to 358 K (85°C). Calculations using a delay figure of merit indicate that f_T, R_b, and C_c are the delay components most affected by low-temperature operation. The feasibility of reduced logic swing operation of bipolar circuits at low temperatures is examined. It is found that successful ECL circuit operation at reduced logic swings is possible provided emitter resistance is kept small and can be used to enhance low-temperature power-delay performance. These data suggest that conventionally designed high-performance bipolar devices are suitable for the low-temperature environment     

SiGe HBT与Si BJT的~(60)Co射线总剂量辐照效应比较

研究了国产结构参数近似的SiGe HBT与Si BJT在60Coγ射线辐照前和不同剂量辐照后性能的变化,并作了比较。辐照后集电极电流Ic变化很小,基极电流Ib明显增大,表明辐照后电流增益的下降主要是由于Ib的退化所导致。当辐照剂量达到10kGy(Si)时,SiGe HBT和Si BJT的最大电流增益分别下降为77%和55%,表明了SiGe HBT具有比Si BJT更好的抗γ射线辐照性能。对辐射损伤机理进行了探讨。     

GaAs-AlxGa1-xAs双异质结激光器的伏安特性

测量了77～300K 范围内 GaAs-AlxGa1-xAs DH 激光器的伏安特性。典型的正向特性曲线可用下式描写:I=I1+I2=Is1exp（AV）+Is1exp（q/nkT V）A 和 n 是只与温度有微弱关系的参数。     

一种快速测量晶体管共射极直流放大倍数(HFE)的方法

晶体管是一种常用的半导体分立器件,共射极直流放大倍数(HFE)是其重要的一个参数,定义为指定集电极和发射极之间的电压(Uce)下、指定集电极电流(Ic)时和基极电流(Ib)的比值.晶体管是电流控制型器件,为达到指定Ic,在测量时通常采用扫描法:逐步增加Ib,测量Ic的值,当到达指定值时停止扫描,计算比值.这种方法效率很低,本文介绍了一种快速测试的方法,借助ATE上参数测量单元(PMU)的加流功能,一次就可以快速测量出放大倍数.     

红外探测器专用前置放大电路低温特性的研究

红外探测系统被广泛地应用于航空航天、军事、通信等领域。前置放大器低温性能的改善直接影响到整个系统探测精度的提高。从理论上分析了MOS器件低温性能参数的变化,设计了一种红外探测器处理电路专用的CMOS低功耗电流型前置放大器,并采用0.35 ?滋m标准CMOS工艺流片,进行了常温(300 K)和低温(77 K)测试。测试结果表明,该运放电路在低温工作时放大倍数线性度良好,功耗等性能得到改善;但是带宽、失调、输入线性范围等性能下降。针对实验结果给出了初步理论分析。