高能电子辐照对三结GaAs激光电池特性的影响

研究了能量为1 MeV的电子辐照对三结GaAs激光电池(LPC)性能的影响。不同剂量电子辐照后三结GaAs LPC光照下的I-V特性测试结果表明，三结GaAs LPC短路电流、开路电压和最大输出功率的衰减随电子辐照剂量的提高而增大。通过测量不同波长激光照射下三结GaAs LPC的宽电压范围I-V曲线，确定了各子电池对应的光生电流，结果显示各子电池光生电流衰减随辐照剂量增加而不同程度地增大，越靠近衬底的子电池电流衰退越严重。利用wxAMPS软件模拟了各子电池光生电流随缺陷密度的变化关系，结合实验和模拟结果得到了各子电池辐照后的缺陷密度及缺陷引入率，结果表明各子电池受电子辐照后的缺陷引入率大致相同，约为6.7。可通过优化各结子电池厚度达到提高三结GaAs LPC抗辐照性能的目的。     

激光辐照对长波HgCdTe光导探测器电学参数的影响

对长波HgCdTe光导探测器进行了低于其永久损伤阈值的变功率激光辐照 ,测量辐照前后器件的电阻 温度特性 ,用电阻 温度特性研究材料参数的方法对实验结果进行拟合 ,结果表明辐照后HgCdTe探测器件的组分变大 ,并由此计算得到探测器性能突变后 ,器件的电子迁移率与电子浓度均有一定程度减小。认为这可能是由于激光辐照的热效应使N型HgCdTe光导器件的表面及体内均产生的一定的变化所致     

GaAs光电导探测器的双束质子改性

介绍了未改性的砷化镓光电导探测器以及经过两束不同能量的质子改性后的砷化镓探测器对X射线的响应,并对它们的输出波形与经过电子改性后的探测器的输出波形进行了比较,结果表明,经过双束质子辐照后的探测器的性能有较大的改善,双束质子改性较电子改性后的探测器有较好的性能.     

电子辐照对GaAs HBT残余电压与饱和电压的影响

研究了GaAs HBT高能电子(～1MeV)辐照的总剂量效应。结果表明,电子辐照后GaAs HBT的基极电流增大,辐照损伤程度随辐照总剂量增加而增加,这和其他研究观察到的现象相同。所不同的是,实验中发现随辐照剂量增大器件集电极饱和电压、残余电压均增大。因此认为,高能电子辐照造成的位移损伤在GaAs HBT集电区和BC结内诱生的大量复合中心使集电极串联电阻增大,以及BE、BC结内形成的复合中心俘获结内载流子使载流子浓度降低造成BE、BC结自建电势差下降是集电极饱和电压和残余电压增加的主要原因。     

GaAs微条粒子探测器的辐照特性

设计了一种能经受高能粒子辐照的GaAs微条粒子探测器.该探测器结构采用金属-半导体-金属结构,其主要几何尺寸是:微条长度为17mm,宽度分别为20、50、100、200、300μm.该探测器在经受电子、中子、γ射线、X射线等高能粒子辐照后,表面金属光亮无损,反向击穿电压最高可达180V,在反偏电压80V时,反向暗电流密度低达31nA/mm2.探测器的最小条宽为20μm.     

多结太阳电池辐射损伤的电致发光研究

建立了电致发光测试方法,对一种国产GaInP/GaAs/Ge三结太阳电池1MeV电子辐照后各子电池的辐照特性进行了研究,并与光谱响应结果进行了比较。讨论了GaInP/GaAs/Ge三结太阳电池的辐射损伤机理。     

激光辐照对长波HgCdTe光导探测器电学参数的影响

对长波HgCdTe光导探测器进行了低于其永久损伤阈值的变功率激光辐照,测量辐照前后器件的电阻-温度特性,用电阻-温度特性研究材料参数的方法对实验结果进行拟合,结果表明辐照后HgCdTe探测器件的组分变大,并由此计算得到探测器性能突变后,器件的电子迁移率与电子浓度均有一定程度减小.认为这可能是由于激光辐照的热效应使N型HgCdTe光导器件的表面及体内均产生的一定的变化所致.     

激光辐照对长滤HgCdTe光导探测器电学参数的影响

对长波HgCdTe光导探测器进行了低于其永久损伤阈值的变功率激光辐照，测量辐照前后器件的电阻－温度特征，用电阻－温度特征研究材料参数的方法对实验结果进行拟合，结果表明辐照后HgCdTe探测器件的组分变大，并由此计算得到探测器性能突变后，器件的电子迁移率与电子浓度均有一定程度减小。认为这可能是由于激光辐照的热效应使N型HgCdTe光导器件的表面及体内均产生的一定的变化所致。     

n-GaN肖特基势垒紫外光探测器的电子辐照效应

研究了n型Au/GaN肖特基势垒紫外光探测器的电子辐照失效机理.从实验中观测到,随着电子辐照注量的不断增加,Au/GaN间辐照诱生的界面态引起器件的击穿电压明显减小,反向漏电流逐渐增大.辐照诱生的深能级缺陷导致紫外光探测器对较长波长光的吸收,使得UV探测器中可见光成分的背景噪声增加.同时,对辐照后的GaN肖特基紫外光探测器进行了100℃以下的退火处理,退火后,器件的电流-电压特性有所改善.     

双面Schottky势垒型GaAs粒子探测器特性

双面肖特基势垒型GaAs粒子探测器由半绝缘砷化镓材料制成,器件结构为金属-半导体-金属结构,该探测器能经受能量为1.5MeV、剂量高达1000kGy的电子、500kGy的γ射线、β粒子、X射线等粒子的辐照测试,辐照后器件击穿曲线坚挺,反向漏电流最低为0.48μA.器件的另一特征是其反向漏电流与X射线的照射量呈线性关系.该探测器在241Am(Ea＝5.48MeV)a粒子辐照下,其最大的电荷收集率和能量分辩率分别为45%和7%.在由90Sr(Eβ=2.27MeV)发出的β粒子辐照下,探测器有最小的电离粒子谱.该探测器对光照也有明显的响应.     

Impedance properties and broad-band operation of GaAs photoconductive detectors

The impedance properties of GaAs ion-implanted photoconductive detectors reveal an interesting effect. The reflection coefficient S11of the photoconductors shows the detector impedance to be a constant resistance with no reactive component over a bandwidth of more than 1.5 GHz at a particular bias voltage. Broad-band matching to the detector load and transit time limited detector response (no RC time constant) are possible due to the absence of reactive components. A model is presented that explains this effect, as well as the superlinear increase in output signal with bias observed with these detectors. Also, no evidence of the long low response tails present in these and similar photoconductors in seen in the S11measurement, lending experimental support to the common theory that these tails are due to the trapping of excess photogenerated minority carries.     

Analysis of a GaAs metal-semiconductor-metal (MSM) photodetectorwith 0.1-μm finger spacing

The temporal response of a GaAs metal-semiconductor-metal (MSM) photodetector with a finger spacing of 0.1 μm is discussed. The intrinsic detector has a minor effect (25% increase) on the full width at half-maximum (FWHM) of the temporal response of the device and its parasitic circuit elements. The analysis indicates that a long time constant due to the decay of holes is solely responsible for this increase. The smallest FWHM for this detector is estimated to be less than 2.5 ps     

Femtosecond excitonic optoelectronics

The authors discuss a novel approach to femtosecond optoelectronics which uses the excitonic response to electric fields as a detector and the excitonic nonlinear response to optical fields as a generator. The sensitivity of the quantum-well exciton to applied electric fields is used to measure electrical transients with femtosecond time resolution. The authors examine several mechanisms for femtosecond electrical pulse generation, including exciton ionization and two-photon absorption, and present measurements of the propagation properties of coplanar striplines on ultrathin semiconductor substrates in the 1-100-THz frequency range. The generation and detection of an electrical pulse with a 180-fs risetime propagating on a coplanar stripline on GaAs/AlGaAs quantum wells are demonstrated     

A GaAs Schottky-barrier photodiode with high quantumefficiency-bandwidth product using a multilayer reflector

A GaAs Schottky-barrier with high quantum efficiency-bandwidth product has been developed by using a GaAs/Al_0.25Ga_0.75 As multilayer reflector. The multilayer reflector structure wa designed by using the scattering matrix method. By growing four pairs of Al_0.25Ga_0.75As (825 Å)/GaAs (330 Å) multilayer reflectors between the undoped GaAs active layer and the buffer layer, a responsivity of 0.6 A/W at λ=0.84 μm was obtained for this device. This represents a 30% improvement over the device without a multilayer reflector. The response speed of the photodiode was measured by the impulse response method, and the results yielded a rise time of 38.45 ps, corresponding to a bandwidth of 9 GHz for this detector     

Growth and characterization of n-type GaAs/AlGaAs quantum well infrared photodetector on GaAs-on-Si substrate

We present in this article device characteristics of molecular beam epitaxy grown GaAs/AlGaAs quantum well infrared photodetectors (QWIP) on a semi-insulating GaAs substrate and on a GaAs-on-Si substrate grown by metalorganic chemical vapor deposition (MOCVD). Important issues for QWIP application such as dark current, spectral response, and absolute responsivity were measured. We find that the detector structure grown on a GaAs-on-Si substrate exhibits comparable dark current and absolute responsivity and a small blue shift in the spectral response. This is the first demonstration of long wavelength GaAs/AlGaAs quantum well infrared photodetector using MOCVD grown GaAs-on-Si substrate and the performance is comparable to a similar detector structure grown on a GaAs substrate.     

Numerical analysis of temporal response of a large exponential-doping transmission-mode GaAs photocathode

The theory of temporal response properties for a large exponential-doping transmission mode GaAs photocathode is discussed in detail. By the introduction of a new concept referred to as “average decay time”, the deficiency usually caused by the boundary condition in the previous calculations is effectively eliminated. The analytical results show that the response time of the new GaAs photocathode can be significantly reduced to several picoseconds in the absence of bias. In addition, the thickness of the GaAs absorption layer we obtained is much larger than that of traditional GaAs photocathodes with the same response time, which means that the novel photocathode with ultrafast time response will have higher yield, especially in near-infrared region.     

A superlattice GaAs/InGaAs-on-GaAs photodetector for 1.3-μmapplications

A metal-semiconductor-metal detector with a InGaAs/GaAs superlattice active layer showing efficient photoresponse up to 1.35 μm is discussed. The active layer with an In composition of approximately 64% is grown by molecular beam epitaxy on a GaAs substrate at 460°C. The large size detector (200×200 μm²) shows bias-dependent DC gain, fast response speed (FWHM <50 ps), and reasonably low dark current     

Saturation properties of large-aperture photoconducting antennas

The authors describe the saturation properties of ultrafast pulsed electromagnetic radiation generated by large-aperture photoconducting antennas as a function of optical excitation fluence. A theory that predicts this effect is presented. The amplitude saturation of the radiation has been observed form antennas incorporating GaAs, InP, and radiation damaged silicon-on-sapphire consistent with theoretical expectations. The radiated fields were measured directly with a time resolution of 0.6 ps with the use of a large-aperture antennas as a detector. From these experimental studies, information about the high-speed response (i.e., the transient carrier mobility in the first few picoseconds after optical excitation) of the photoconductors incorporated in the antenna can be obtained under conditions of high applied electric fields and optical fluences     

Vertical integration of a GaAs/AlGaAs quantum-well laser and along-wavelength quantum-well infra-red photodetector

A short-wavelength (~0.8 μm) GaAs/AlGaAs graded-index separate-confinement heterostructure quantum-well laser has been monolithically integrated with a long-wavelength (~8 μm) GaAs/AlGaAs multiple-quantum-well infra-red photodetector on a semi-insulating GaAs substrate by molecular beam epitaxy. The vertical integration method is used and the combined structure is a pinin structure. Both the laser and detector exhibit excellent characteristics. At room temperature, the ridge waveguide laser has an extremely low threshold current of 25 mA and a differential quantum efficiency above 65% with a stripe width of 20 μm. The quantum-well detector has a peak response at 8 μm and a responsivity of 0.7 A/W     

Optical characteristics of InGaP/GaAs HPTs

In this paper, we examined the optical characteristics of InGaP/GaAs heterojunction phototransistor (HPT) directly compared with AlGaAs/GaAs HPT for the first time. Because of its inherent good electrical properties, the InGaP/GaAs HPT produced a high optical gain of about 61 at V_C=3 V, I_B=2 μA, for an input optical power of 1.23 μW. This is 2.5 times as high as that of the AlGaAs/GaAs HPT. In the transient response, the InGaP/GaAs HPT was a little inferior to the AlGaAs/GaAs HPT. This is due to the longer time delay caused by the photo-generated hole accumulation at the interface of heterojunction. The extended response time can be overcome by using a small load resistance in conjunction with the advantage of the superior optical gain