Highly sensitive In0.53Ga0.47As/InP Hallsensors grown by MOVPE

High performance InP/InGaAs Hall sensors appropriate for applications requiring high sensitivity at low power dissipation, good linearity, low temperature sensitivity, and high resolution are reported. The layer structures grown by MOVPE combine a high mobility In _0.53Ga_0.47As channel with isolation by semi-insulating InP. With this design bias current related sensitivities up to 760 V/AT at sheet resistances below 840 Ω/square have been achieved, allowing high output signals at low power dissipation. Due to the active layer isolation by semi-insulating InP, bias currents are not limited by channel pinch-off or junction breakdown. This leads to absolute sensitivities as high as 12.5 V/T. Linearity errors are lower than -0.8% up to magnetic fields of 0.5 T. Temperature coefficients of the sensitivity were measured for different donor concentrations of the active layer. The lowest value of -0.07%/K was found for a doping of 10 ¹⁶ cm^-3, in accordance with theoretical predictions. High signal-to-noise ratios corresponding to minimal detectable fields of 50 nT/Hz^l/2 and 160 nT/Hz^l/2, respectively, were measured at 1 kHz and 100 Hz     

Hot-electron transport in In0.53Ga0.47As

A set of physical constants for In_0.53Ga_0.47As as required for transport calculations is obtained by reviewing the literature. Velocities for fields up to 100 kV/cm, calculated by the Monte Carlo method using these constants, are presented for the temperatures of 95 and 300 K. The calculated values are found to be in good agreement with the available experimental results.     

High-performance InP/In0.53Ga0.47As/InPdouble HBTs on GaAs substrates

InP/In_0.53Ga_0.47As/InP double heterojunction bipolar transistors (HBTs) were grown on GaAs substrates. A 140 GHz power-gain cutoff frequency f_max and a 207 GHz current-gain cutoff frequency f_τ were obtained, presently the highest reported values for metamorphic HBTs. The breakdown voltage BV_CEO was 5.5 V, while the dc current gain β was 76. High-thermal-conductivity InP metamorphic buffer layers were employed in order to minimize the device-thermal resistance     

高量子效率InP/In0.53Ga0.47As/InP红外光电阴极模拟

将In0.53Ga0.47As吸收层设计为多个薄层,通过不同浓度掺杂实现吸收层杂质指数分布,建立了InP/In0.53Ga0.47As/InP红外光电阴极模型,在皮秒级响应时间的前提下模拟了吸收层厚度、掺杂浓度和阴极外置偏压对阴极内量子效率的影响,给出了光电子在吸收层和发射层的一维连续性方程和边界条件,计算了光电子克服激活层势垒发射到真空中的几率,进而获得阴极外量子效率随上述三个因素的变化规律,结果表明,吸收层掺杂浓度在1015~1018 cm-3范围内变化时,内量子效率变化很小;随着吸收层厚度在0.09~0.81 m内增大,内量子效率随之增大;随着外置偏压升高,内量子效率先增大后趋于平稳。文中给出一组既能获得高量子效率又能有快时间响应的阴极设计参数,理论上1.55 m入射光可以获得8.4%的外量子效率,此时响应时间为49 ps。     

A resistive-gate In0.53Ga0.47As/InPheterostructure CCD

The first InGaAs/InP charge-coupled device (CCD) is demonstrated, exhibiting a charge transfer efficiency (CTE) of 0.98 at 13 MHz and 1 GHz. Cooling the device improves the CTE to greater than 0.99 at 13-MHz clock frequency. The 0.76-eV In_0.53Ga_0.47As bandgap makes this structure applicable to direct-detection short-wavelength infrared (SWIR) imagers     

Characterization of surface-undoped In0.52Al0.48As/In0.53Ga0.47As/InP high electron mobilitytransistors

High-performance 0.3-μm-gate-length surface-undoped In_0.52 Al_0.48As/In_0.53Ga_0.47As/InP high-electron-mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE) have been characterized and compared with a surface-doped structure. At 18 GHz, the surface-undoped HEMT has achieved a maximum stable gain (MSG) of 19.2 dB compared to 16.0 dB for the surface-doped structure. The higher MSG value of the surface-undoped HEMTs is obtained due to the improved g_m/g₀ ratio associated with the surface-induced electric field spreading effect. Comparison of identical 0.3-×150-μm-gate devices fabricated on surface-undoped and -doped structures has shown greatly improved gate leakage characteristics and much lower output conductance for the surface-undoped structure. It is demonstrated that the surface potential, modulated by different surface layer designs, affects the charge control in the conducting channel, especially the carrier injection into the buffer, resulting in excess output conductance. Several millimeter-wave coplanar waveguide (CPW) monolithic distributed amplifiers have been successfully fabricated by using the surface-undoped HEMT structure. A high gain per stage distributed amplifier with 170-dB±1-dB small-signal gain across a frequency band of 24-40 GHz, a W-band monolithic integrated circuit with 6.4-dB gain at 94 GHz, and a broad bandwidth distributed amplifier with 5-dB gain across a frequency band of 5 to 100 GHz have been demonstrated by using the surface-undoped structures     

Temporal response characteristics of a In0.53Ga0.47As/InP quantum well phototransistor

An investigation of multiple-quantum-well heterojunction phototransistors with InGaAs/InP quantum wells in the collector and InGaAsP base is discussed. The design of the structure ensures that light is absorbed only in the quantum-well region, thus providing a way to study the correlation between quantum well and phototransistor carrier dynamics. Moreover, since the operation of a n-p-n phototransistor is governed by hole injection into the base, the transient behavior of the device reflects the hole dynamics in the multiple-quantum-well region. The response of the device to picosecond optical pulses shows strong dependence on bias conditions: from device response determined by minority carrier recombination time (~2 ns) at high base-emitter bias, to current time constant dominated response (~50 ps) at low base-emitter bias. The field dependent escape times of carriers from the quantum wells under different bias conditions are obtained (10-100 ps) and are seen to affect the risetime of the transistor to pulsed photoexcitation     

In0.53Ga0.47As/InP floating guard ringavalanche photodiodes fabricated by double diffusion

In_0.53Ga_0.47As/InP separate absorption and multiplication region avalanche photodiodes (SAM-APDs) with doubly diffused floating guard rings have been demonstrated. The planar, front-side illuminated devices are easily fabricated and incorporate strong guarding against edge and surface breakdown. Edge gain is suppressed both by the action of the floating guard rings and by the grading of the p-n junction at the outer edges of the active region that results from the second diffusion. Uniform gains as high as 85 have been measured at multiplied dark currents <100 nA. Multiplied dark currents below 5 nA have been measured at 90% of breakdown, with capacitances below 400 fF for front-side illuminated devices. The low values of dark current and capacitance, as well as the ease of fabrication, make the devices well suited for fiber-optic applications     

Many body effects in the luminescence of In0.53Ga0.47As/InP quantum wires

We have investigated many body effects in the one-dimensional neutral electron-hole plasma of In_0.53Ga_0.47As/InP quantum wires. By using high laser excitation the active section of the wires was filled up to the InP barrier. The luminescence band shows up to four features which can be assigned to lateral subband transitions in the quantum wires. With increasing excitation intensities we observe a red shift of the emission due to the interparticle interaction among the carriers. By using theoretical line shape calculations the temperature and the density for the electron-hole plasma and the band gap renormalization were determined. The decreasing band gap renormalization with increasing subband index was traced to the density dependence of the exchange energy.     

InP/In0.53Ga0.47As heterojunction bipolartransistors with a carbon-doped base grown by MOCVD

InP/In_0.53Ga_0.47As heterojunction bipolar transistors (HBTs) utilizing a carbon-doped base have been demonstrated. The devices were grown by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) using carbon tetrachloride (CCl₄) as the p-type dopant source. These devices exhibit a DC common-emitter current gain of 50 and an emitter-base junction ideality factor of 1.29 in a structure for which no undoped spacer layer was employed at the emitter-base junction. These preliminary results suggest that C-doping of In_0.53Ga_0.47As may be a suitable alternative to Zn in MOCVD-grown InP/In_0.53Ga_0.47As HBTs     

Impact of surface layer on In0.52Al0.48As/In0.53Ga0.47As/InP high electron mobilitytransistors

The surface potential of FETs has shown a strong effect on the channel potential and charge control in the channel. A study of the role of undoped versus doped cap layers in In_0.52Al_0.48As-In_0.53Ga_0.47 As-InP high-electron-mobility transistors (HEMT) is discussed. As the result of surface potential effect, direct comparison of 0.3×150-μm² gate devices yielded improved gate breakdown characteristics and a DC output conductance of less than 15 mS/mm for the surface undoped structure compared to 50 mS/mm for the doped structure. The surface undoped MEMT achieved a very high maximum stable gain of 19.2 dB compared to 16.0 dB for the surface doped HEMT at 18 GHz, largely due to the improved g_m/g ₀ ratio. This study demonstrates that control of the surface potential in In_0.52Al_0.48As-In_0.53Ga _0.47As-InP HEMTs is consistent with the effect of a gate recess in MESFETs. This study also shows that, in achieving high-gain applications of HEMTs, the surface potential near the gate edge should be optimized through unconventional surface layer design     

Demonstration of aluminum-free metamorphic InP/In0.53Ga0.47As/InP double heterojunction bipolar transistors on GaAssubstrates

We report, for the first time, the successful fabrication of aluminum-free metamorphic (MM) InP/In_0.53 Ga_0.47 As/InP double heterojunction bipolar transistors (DHBTs) on GaAs substrates with a linearly graded In_xGa_1-xP buffer grown by solid-source molecular beam epitaxy (SSMBE). Devices with 5×5 μm² emitters display a peak current gain of 40 and a common-emitter breakdown voltage (BV_CE0) higher than 9 V, a current gain cut-off frequency (f_T) of 48 GHz and a maximum oscillation frequency (f_max) of 42 GHz. A minimum noise figure of 2.9 dB and associated gain of 19.5 dB were measured at a collector current level of 2.6 mA at 2 GHz. Detailed analysis suggests that the degradation of the base-emitter heterojunction interface and the increase of bulk recombination are the most probable causes for the poorer device performance of current metamorphic HBTs compared with lattice-matched HBTs     

Tunneling between two quantum wells: In0.53Ga0.47As/InP versus GaAs/Al0.35Ga0.65As

The electron transfer from a narrow to a wide quantum well through a thin barrier is studied in the non-resonant case by time-resolved photoluminescence. The two systems In_0.53Ga_0.47As/InP and GaAs/Al_0.35Ga_0.65As are compared. Space charge effects are investigated and discussed. Contributions of holes to the tunneling process are determined.     

Long-wavelength In0.53Ga0.47As metamorphicp-i-n photodiodes on GaAs substrates

Metamorphic In_0.53Ga_0.47As p-i-n photodiodes on GaAs substrate exhibiting the lowest dark current ever reported were fabricated and characterized. Their dark current, DC and RF performances were measured and compared for devices of different sizes. Typical dark current for 15-μm-diameter devices was 600 pA under 5-V reverse bias, corresponding to a dark current density of 3.40×10^-4 A/cm². Typical responsivity measured with 1.55-μm optical radiation was 0.55 A/W corresponding to an external quantum efficiency of 44%. The electrical 3 dB bandwidths of the photodiodes with diameters smaller than 20 μm were over 20 GHz     

Analysis of the dark current and photoresponse of In0.53Ga0.47As/InP avalanche photodiodes

The doping profiles, current-voltage (I–V) and photoresponse characteristics of five In_0.53Ga_0.47As/InP avalanche photodiode (APD) wafers are presented. A detailed analysis indicates that the dark current is due largely to generation and recombination of carriers in the diode bulk, and in some wafers tunneling at the p-n junction is dominant near breakdown (V_B). In some cases, significant surface currents are also observed. In three high-performance wafers, however, low primary dark currents (～5 nA) with no evidence for tunnelling at 0.99 V_B have been obtained. In addition, microplasmas have been found in some wafers, due to local breakdown possibly arising from crystalline defects. Nevertheless, we report uniform gains as high as 100. The dark current and gain characteristics of these devices are among the best reported to date for In_0.53Ga_0.47As/InP APDs.Finally, the response of the APDs to fast optical pulses has been analyzed at both low and high illumination intensity. The slow speed of response, which has been reported elsewhere, is considered in detail and is found to be due to charge pile-up at the abrupt n-In_0.53Ga_0.47As/n-InP heterointerface which is characteristic of our devices. Using an analysis of the response time thermal activation energy along with the transient pulse shape, we infer that the heterointerfaces are graded over a length of $\text{2}\text{L}\text{≌ 300}\text{A}\text{?}$. The model predicts that fast response can be obtained for heterointerface grading lengths of $\text{2}\text{L}\text{? 500}\text{A}\text{?}$, depending on the epitaxial layer doping and extent of penetration of the depletion region into the In_0.53Ga_0.47As layer at breakdown.     

Positive temperature dependence of the electron impact ionizationcoefficient in In0.53Ga0.47As/InP HBTs

Impact ionization is a major limiting factor to the maximum operating voltage of InGaAs-based, high-speed transistors. In this work, data on the positive temperature dependence of the electron impact ionization coefficient α_n in In_0.53Ga_0.47As at medium-low electric fields are reported for the first time. The increase of α_n with temperature is opposite to the behavior normally observed in most semiconductors. This anomalous behavior implies the onset of a positive feedback between power dissipation and avalanche generation which may adversely affect the power handling capability of In_0.53Ga _0.47As-based devices, and which should be taken into account in device thermal modeling. In the experimental procedure, based on the measurement of the multiplication factor M-1 in npn In_0.53Ga _0.47As/InP Heterojunction Bipolar Transistors (HBT), particular care has been taken in order to rule out possible spurious, temperature-dependent contributions to the measured multiplication current     

High-performance In0.52Al0.48As/In0.53Ga0.47As HFET compatible with optical-detectorintegration

The authors report the successful demonstration of a 1.0-μm gate InAlAs/InGaAs heterojunction FET (HFET) on top of thick InGaAs layers using lattice-matched molecular beam epitaxy (MBE). This scheme is compatible with metal-semiconductor-metal (MSM) photodetector fabrication. The authors measured the performance of InAlAs/InGaAs HFETs from 0 to 40 GHz. Device performance is characterized by peak extrinsic transconductances of 390 mS/mm and as-measured cutoff frequencies up to 30 GHz for a nominal 1.0-μm-gate-length HFET. HFET device measurements are compared for samples growth with and without the thick underlying InGaAs optical-detector absorbing layer     

In0.53Ga0.47As/In0.52Al0.48As雪崩光电二极管的数值模拟研究

建立了SACM型In0.53Ga0.47As/In0.52Al0.48As雪崩光电二极管(APD)的分析模型,通过数值研究和理论分析设计出高性能的In0.53Ga0.47As/In0.52Al0.48As APD。器件设计中,一方面添加了In0.52Al0.48As势垒层来阻挡接触层的少数载流子的扩散,进而减小暗电流的产生;另一方面,雪崩倍增区采用双层掺杂结构设计,优化了器件倍增区的电场梯度分布。最后,利用ATLAS软件较系统地研究并分析了雪崩倍增层、电荷层以及吸收层的掺杂水平和厚度对器件电场分布、击穿电压、IV特性和直流增益的影响。优化后APD的单位增益可以达到0.9 A/W,在工作电压(0.9 Vb)下增益为23.4,工作暗电流也仅是纳安级别(@0.9 Vb)。由于In0.52Al0.48As材料的电子与空穴的碰撞离化率比InP材料的差异更大,因此器件的噪声因子也较低。     

High-frequency performance of metamorphic InP/In0.53Ga0.47As/InP DHBT in common base configuration on GaAs substrates

In this work, we report the detailed high-frequency noise and power characterization of metamorphic InP double heterojunction bipolar transistors in common base configuration. The noise and power performances were investigated for 5×10 μm² device. A minimum noise figure of 2.3 dB with an associated gain of 14.5 dB at 2 GHz, and a maximum output power of 13.0 dBm with a power added efficiency of 47.8% at 2.4 GHz were obtained.     

Variational results for electron mobility in modulation-doped In0.53Ga0.47As/InP single symmetric quantum wells

In this paper, the low-field carrier mobility is investigated for quasi-2D electrons in a n-doped In_0.53Ga_0.47As/InP single symmetric quantum well. An accurate variational scheme is developed in view to determine the subband structure in this lattice-matched heterostructure. In this scheme, the Schrödinger-Poisson coupled equations are solved observing adequate matching conditions at the heterointerfaces, as well as exchange-correlation corrections to the Hartree potential. The results allowed us to compute the main scattering rates. Some interchanges in these scattering rates were found with respect to the limitation of electron mobility by varying the well and the spacer widths.