Calculation of the band structure of semiconductor quantum wells using scattering matrices

The transfer-matrix method widely used in the calculation of the band structure of semiconductor quantum wells is found to have limitations due to its intrinsic numerical instability. It is pointed out that the numerical instability arises from free-propagating transfer matrices. A new scattering-matrix method is developed for the multiple-band Kane model within the envelope-function approximation. Compared with the transfer-matrix method, the proposed algorithm is found to be more efficient and stable. A four-band Kane model is used to check the validity of the method and the results are found to be in good agreement with earlier calculations.

Band structure parameters of zinc-blende GaN, AlN and their alloys Ga1-xAlxN

The electronic properties of wide energy gap zinc-blende structure GaN, AlN and their alloys Ga1-xAlxN are investigated using the empirical pseudopotential method. Electron and hole Effective mass parameters, hydrostatic and shear deformation potential constants of the valence band at Gamma and those of the conduction band at Gamma and X are obtained. The energies of Gamma, X, L conduction valleys of Ga1-xAlxN alloy versus Al fraction x are also calculated. The information will be useful for the design of lattice mismatched heterostructure optoelectronic devices in the blue light range.

An asymmetric MOSFET-C band-pass filter with on-chip charge pump auto-tuning

An asymmetric MOSFET-C band-pass filter(BPF)with on chip charge pump auto-tuning is presented.It is implemented in UMC (United Manufacturing Corporation)0.18μm CMOS process technology. The filter system with auto-tuning uses a master-slave technique for continuous tuning in which the charge pump OUtputs 2.663 V, much higher than the power supply voltage, to improve the linearity of the filter. The main filter with third order low-pass and second order high-pass properties is an asymmetric band-pass filter with bandwidth of 2.730-5.340 MHz. The in-band third order harmonic input intercept point(HP3) is 16.621 dBm,wim 50 Ω as the source impedance. The input referred noise iS about 47.455μVrms. The main filter dissipates 3.528 mW while the auto-tuning system dissipates 2.412 mW from a 1.8 V power supply. The filter with the auto-tuning system occupies 0.592 mm~2 and it can be utilized in GPS (global positioning system)and Bluetooth systems.

A Low Power Dissipation Wide-Band CMOS Frequency Synthesizer for a Dual-Band GPS Receiver

This paper presents a wide tuning range CMOS frequency synthesizer for a dual-band GPS receiver,which has been fabricated in a standard 0.18μm RF CMOS process. With a high Q on-chip inductor, the wide-band VCO shows a tuning range from 2 to 3.6GHz to cover 2.45 and 3.14GHz in case of process corner or temperature variation,with a current consumption varying accordingly from 0.8 to 0.4mA,from a 1.8V supply voltage. Measurement results show that the whole frequency synthesizer consumes very low power of 5.6mW working at L1 band with in-band phase noise less than - 82dBc/Hz and out-of-band phase noise about - ll2dBc/Hz at 1MHz offset from a 3. 142GHz carrier. The performance of the frequency synthesizer meets the requirements of GPS applications very well.

U型凹槽电极硅MSM结构光电探测器的研制

为了提高硅MSM结构光电探测器的光电响应度,制备了U型凹槽电极结构的探测器。5 V偏压下,对650 nm波长入射光的绝对光电响应度测试表明,凹槽电极结构的探测器最大光电响应度值为0.486 A/W,比同样尺寸的平版结构光电探测器提高了约6倍。文中也对比了具有抗反射膜和不具有抗反射膜的器件相对响应光谱的差别,并且比较分析了叉指间隙分别为5μm和10μm器件光电响应的不同。

AIGaN/GaN HEMTs Power Amplifier MIC with Power Combining at C-Band

A power amplifier MIC with power combining based on AlGaN/GaN HEMTs was fabricated and measured. The amplifier consists of four 10×120μm transistors. A Wilkinson splitters and combining were used to divide and combine the power. By biasing the amplifier at V_(DS) =40V, I(DS)= 0. 9A, a maximum CW output power of 41. 4dBm with a maximum power added efficiency (PAE) of 32. 54% and a power combine efficiency of 69% was achieved at 5. 4GHz.

A Wide-Band Low Noise Amplifier for Terrestrial and Cable Receptions

We present the design of a wide-band low-noise amplifier （LNA） implemented in 0.35μm SiGe BiCMOS technology for cable and terrestrial tuner applications. The LNA utilizes current injection to achieve high linearity. Without using inductors, the LNA achieves 0.1 ～ 1GHz wide bandwidth and 18. 8dB gain with less than 1.4dB of gain variation. The noise figure of the wideband LNA is 5dB, and its 1dB compression point is - 2dBm and IIP3 is 8dBm. The LNA dissipates 120mW of power with a 5V supply.

A Wide-Band High-Linearity Down-Conversion Mixer for Cable Receptions

We analyze a wide-band,high-linearity down-conversion mixer for cable receptions that is implemented in 0. 35μm SiGe BiCMOS technology. The bandwidth of the RF （radio frequency） input covers the range from 1 to 1.8GHz. The measured input power at the - 1dB compression point of the mixer reaches ＋ 14.23dBm. The highest voltage conversion gain is 8. 31dB, while the lowest noise figure is 19.4dB. The power consumed is 54mW with a 5V supply. The test result of the down-conversion mixer is outlined.

X-Band GaN Power HEMTs with Power Density of 2.23W/mm Grown on Sapphire by MOCVD

The growth,fabrication,and characterization of 0.2μm gate-length AlGaN/GaN HEMTs,with a high mobility GaN thin layer as a channel,grown on (0001) sapphire substrates by MOCVD,are described.The unintentionally doped 2.5μm thick GaN epilayers grown with the same conditions as the GaN channel have a room temperature electron mobility of 741cm2/(V·s) at an electron concentration of 1.52×1016 cm-3.The resistivity of the thick GaN buffer layer is greater than 108Ω·cm at room temperature.The 50mm HEMT wafers grown on sapphire substrates show an average sheet resistance of 440.9Ω/□ with uniformity better than 96%.Devices of 0.2μm×40μm gate periphery exhibit a maximum extrinsic transconductance of 250mS/mm and a current gain cutoff frequency of77GHz.The AlGaN/GaN HEMTs with 0.8mm gate width display a total output power of 1.78W (2.23W/mm) and a linear gain of 13.3dB at 8GHz.The power devices also show a saturated current density as high as 1.07A/mm at a gate bias of 0.5V.

Wide-Band Polarization-Independent Semiconductor Optical Amplifier Gate with Tensile-Strained Quasi-Bulk InGaAs

A semiconductor optical amplifier gate based on tensile-strained quasi-bulk InGaAs is developed. At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band-filling effect.Moreover, the most important is that very low polarization dependence of gain (＜0. 7dB),fiber-to-fiber lossless operation current (70～90mA) and a high extinction ratio (＞50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm)and the whole L band (1570～ 1610nm). The gating time is also improved by decreasing carrier lifetime. The wideband polarization-insensitive SOA-gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.

High-Power and High-Efficiency 650nm-Band AlGaInP Visible Laser Diodes Fabricated by Ion Beam Etching

High power and high-slope efficiency 650nm band real-refractive-index ridge waveguide AlGaInP laser diodes with compressive strained MQW active layer are formed by pure Ar ion beam etching process.Symmetric laser mesas with high perpendicularity,which are impossible to obtain by traditional wet etching method due to the use of a 15°-misoriented substrate,are obtained by this dry etching method.Laser diodes with 4μm wide,600μm long and 10%/90% coat are fabricated.The typical threshold current of these devices is 46mA at room temperature,and a stable fundamental-mode operation over 40mW is obtained.Very high slope efficiency of 1.4W/A at 10mW and 1.1W/A at 40mW are realized.

RCE photodiodes at wavelength band of 1.06 μm

Resonant cavity enhancement (RCE) typed optical detector and modulator which operating at wavelength band of 1.06 μm is reported. The peak quantum efficiency of detector is reasonably high as 50% without bias, and the photocurrent contrast ratio of modulator is 3.6 times at -3.5 V as compared to 0 V. The incident angle dependence of RCE device's photoelectric response is investigated carefully.

GaN基MSM结构紫外光探测器

在蓝宝石(0001)衬底上采用低压金属有机物公学气相沉积(MOCVD)方法生长GaN外延层，以此为材料，制作了暗电流很小的金属半导体金属（MSM）结紫外光探测器，测量了该紫外光探测器的暗电流和360nm波长光照下的光电流曲线，光响应曲线和响应度随偏压变化的曲线，该紫外光线探测器在5V偏压时暗电流为1.03nA,在10V 偏压时暗电流为15.3nA，在15V偏压下该紫外光探测器在366nm 波长处的响应度达到0.166A/W,在365nm波长左右有陡峭的截止边.从0-15V,该紫外光探测器在360nm波长处的响应度随着偏压的增加而增大.详细地分析了该紫外光探测器的暗电流,光电流,响应度随偏压变化的关系.

MSM光探测器的等效电路模型

国家自然科学基金

MSM光探测器的直流特性

在稳态条件下金属-半导体-金属(MSM)光探测器的光电流一维模型可以通过求解电流连续方程和传输方程来建立并求解。在这种条件下，器件内部的载流子分布情况和总体光电流可以得到解析解而不用数值方法求解。该文从电流连续方程和传输方程出发详细推导了这一过程，并将这一结果应用于具体的InGaAs MSM光探测器的直流等效电路模型上，取得了很好的效果。