氧化钒(VOx)作为热敏材料已经广泛应用在非制冷红外探测器中,其中热敏材料的性能对于最终器件性能的影响尤为关键。为了研究钨元素摻杂对氧化钒热敏薄膜材料的相变温度、热滞宽度、低温时的电阻温度系数的影响以及对探测器性能指标的影响,利用微电子加工工艺制备了钨摻杂与非钨摻杂氧化钒溅射薄膜红外探测器件,并利用黑体测试系统结合锁相放大器和频谱分析仪对器件性能指标进行了测试。结果表明,相比非钨掺杂器件,钨掺杂器件的相变温度降低了16℃左右,热滞宽度缩短了5℃左右,器件的响应电压则提高了0.15 m V,单位带宽噪声均方根电压降低了15 n V·Hz-1/2,从而使器件探测率提高。当辐射信号的调制频率为80 Hz时,非钨掺杂氧化钒探测器的探测率D*值为1.67×108cm·Hz1/2/W,而钨掺杂氧化钒探测器的探测率D*值为1.85×108cm·Hz1/2/W。可见,钨掺杂氧化钒探测器的探测率较非钨掺杂氧化钒探测器的探测率高。
The self-assembled growth of InAs/GaAs quantum dots by molecular beam epitaxy is conducted by optimizing several growth parameters,using a one-step interruption method after island formation.The dependence of photoluminescence on areal quantum-dot density is systematically investigated as a function of InAs deposition,growth temperature and arsenic pressure.The results of this investigation along with time-resolved photoluminescence measurements show that the combination of a growth temperature of 490 C,with a deposition rate of 0.02 ML/s,under an arsenic pressure of 1×10 6Torr(1 Torr=1.33322×102Pa),provides the best compromise between high density and the photoluminescence of quantum dot structure,with a radiative lifetime of 780 ps.The applicability of this 5-layer quantum dot structure to high-repetition-rate pulsed lasers is demonstrated with the fabrication and characterization of a monolithic InAs/GaAs quantum-dot passively mode-locked laser operating at nearly 1300 nm.Picosecond pulse generation is achieved from a two-section laser,with a^19.7-GHz repetition rate.
李密锋倪海桥丁颖Bajek DavidKong LiangCataluna Maria Ana牛智川
A resonant cavity-enhanced(RCE) quantum dot(QD) field-effect transistor(RCEQDFET) is designed for singlephoton detection in this paper. Adding distributed Bragg reflection(DBR) mirrors to the single-photon detector(SPD), we improve the light absorption efficiency of the SPD. The effects of the reflectivity of the mirrors, the thickness and light absorption coefficient of the absorbing layer on the detector's light absorption efficiency are investigated, and the resonant cavity is determined by using the air/semiconductor interface as the mirror on the top. Through analyzing the relationship between the refractive index of AlxGa1-xAs and Al component, we choose AlAs/Al0.15Ga0.85 As as the material of the mirror on the bottom. The pairs of AlAs/Al0.15Ga0.85 As film are further determined to be 21 by calculating the reflectivity of the mirror. The detector is fabricated from semiconductor heterostructures grown by molecular beam epitaxy. The reflection spectrum, photoluminescence(PL) spectrum, photocurrent response, and channel current of the detector are tested and the results show that the RCEQDFET-SPD designed in this paper has better performances in photonic response and wavelength selection.
采用分子束外延技术对δ掺杂GaAs/AlxGa1 xAs二维电子气(2DEG)样品进行了生长.在样品生长过程中,分别改变掺杂浓度(Nd)、空间隔离层厚度(Wd)和AlxGa1 xAs中Al组分(xAl)的大小,并在双温(300 K,78 K)条件下对生长的样品进行了霍尔测量;结合测试结果,分别对Nd,Wd及xAl与GaAs/AlxGa1 xAs 2DEG的载流子浓度和迁移率之间的关系规律进行了细致的分析讨论.生长了包含有低密度InAs量子点层的δ掺杂GaAs/AlxGa1 xAs2DEG样品,采用梯度生长法得到了不同密度的InAs量子点.霍尔测量结果表明,随着InAs量子点密度的增加,GaAs/AlxGa1 xAs 2DEG的迁移率大幅度减小,实验中获得了密度最低为16×108/cm2的InAs量子点样品.实验结果为内嵌InAs量子点的δ掺杂GaAs/AlxGa1 xAs 2DEG的研究和应用提供了依据和参考.
