Narrow-gate In0.53Ga0.47As junctionfield-effect transistors as tunable resistors for long-wavelengthintegrated optical receivers

The fabrication of In_0.53Ga_0.47As junction field-effect transistors (JFETs) for use as active feedback resistors in integrated transimpedance photoreceivers is described. Transistors using both air-bridge and non-air-bridge technologies are described. Varying the gate-to-source voltage (V_GS) allows the output resistance to be tuned continuously between 3 and 40 kΩ with a drain-to-source shunt capacitance of less than 10 fF. The temperature coefficient of the output resistance is between -5 and -20 Ω/°C (for V_GS less than the pinch-off voltage). The combination of large resistance and low shunt capacitance can result in high receiver sensitivity without sacrificing amplifier dynamic range. The feedback FETs are fabricated adjacent to 1.8-μm gate JFETs with transconductances of 110 mS/mm and gate-to-source capacitances of 1.3 pF/mm     

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.     

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     

Monolithically integrated receiver front end: In0.53Ga0.47As p-i-n amplifier

Monolithically integrated InGaAs p-i-n amplifiers have been successfully fabricated. The structure utilizes a vertical integration of a p-i-n diode and recessed-gate InP MISFETs, while maintaining a planar surface for fine-line photolithography. The preamplifier consists of a gain stage and a buffer stage, both made of InP MISFETs with aluminium phosphorous oxide as gate insulator. At 400 Mb/s, the receiver sensitivity is better than -27 dBm for 1×10^-9 bit error rate     

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     

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。     

Thin film pseudomorphicAlAs/In0.53Ga0.47As/InAs resonant tunnellingdiodes integrated onto Si substrates

We report high peak-to-valley current ratio (PVR) resonant tunneling diodes (RTDs) bonded to silicon. Pseudomorphic AlAs/In_0.53Ga_0.47As/InAs resonant tunneling diode structures grown on semi-insulating InP with peak-to-valley current ratios as high as 30 at 300 K have been separated from the growth substrate and bonded to silicon substrates coated with Si₃N ₄, forming thin film devices. In addition, thin film multiple stack RTD structures have been bonded to silicon substrates. The I-V characteristics of both the single and multi-stacked thin film RTD's exhibit no signs of degradation after bonding to the host substrate. These results are the first successful demonstration of InP based electronics bonded to a silicon host substrate and enable the integration of RTDs with conventional silicon circuitry     

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     

High-frequency submicrometerAl0.48In0.52As/In0.53Ga0.47As heterostructure bipolar transistors

The high speed scaling of an Al_0.48In_0.52As/In_0.53Ga_0.47 As submicrometer heterostructure bipolar transistor (HBT) is presented. Transistors with emitter dimensions of 0.5×11 and 3.5×3.5 μm² exhibit unity current-gain cutoff frequencies of 63 and 70 GHz, respectively. Emitter current density greater than 3.3×10⁵ A/cm² is demonstrated in a submicrometer AlInAs/InGaAs HBT. The analysis shows that the device speed is limited by the parasitic collector charging time     

In0.52Al0.48As/In0.53Ga0.47As double-heterojunction p-n-p bipolar transistors grown bymolecular beam epitaxy

P-n-p In_0.52Al_0.48As/In_0.53Ga_0.47 As double-heterojunction bipolar transistors with a p⁺-InAs emitter cap layer grown by molecular-beam epitaxy have been realized and tested. A five-period 15-Å-thick In_0.53Ga_0.47As/InAs superlattice was incorporated between the In_0.53Ga_0.47As and InAs cap layer to smooth out the valence-band discontinuity. Specific contact resistance of 1×10^-5 and 2×10^-6 Ω-cm² were measured for nonalloyed emitter and base contacts, respectively. A maximum common emitter current gain of 70 has been measured for a 1500-Å-thick base transistor at a collector current density of 1.2×10³ A/cm². Typical current gains of devices with 50×50-μm² emitter areas were around 50 with ideality factors of 1.4     

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     

MetamorphicIn0.53Ga0.47As/In0.52Al0.48As HEMTs on germanium substrates

We report for the first time the successful epitaxial growth and processing of high-performance metamorphic high electron mobility transistors (HEMTs) on Ge substrates, with a transconductance of 700 mS/mm and a saturation channel current of 650 mA/mm. To reduce parasitic capacitances due to the conductive substrate, a dry etch method based on CF₄ and O₂ reactive ion etching (RIE) is developed for selective substrate removal. Devices with 0.2 μm gate length display an increase of the extrinsic cut-off frequency f_T from 45 GHz before, to 75 GHz after substrate removal, whereas the maximum oscillation frequency f_max increases from 68 GHz to 95 GHz. Based on this excellent rf performance level, in combination with the highly selective thinning process, we think that Ge as a sacrificial substrate is a promising candidate for the integration of thinned individual HEMTs with passive circuitry on low-cost substrates. This could result in low-cost advanced hybrid systems for mass-market millimeter wave applications     

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     

Waveguide In0.53Ga0.47As-In0.52Al0.48As avalanche photodiode

A high-speed waveguide In_0.53Ga_0.47As-In_0.52Al_0.48 As separate absorption, charge, and multiplication avalanche photodiode suitable for operation at 1.55 μm has been demonstrated, a unity-gain bandwidth of 27 GHz was achieved with a gain-bandwidth product of 120 GHz     

Gate-length dependence of DC and microwave properties ofsubmicrometer In0.53Ga0.47As HIGFETs

In_0.52Al_0.48As/In_0.53Ga_0.47 As/InP heterostructure insulated-gate field-effect transistors (HIGFETs) with gate lengths from 1.1 and 0.3 μm have been fabricated, and their electrical performance is characterized at DC and microwave frequencies. The refractory-gate self-aligned process, applied to devices with In_0.53Ga_0.47As channels, yields an unprecedented combination of very-high speed and excellent uniformity. HIGFETs with L_g=0.6 μm showed average peak transconductance g_m of 528 mS/mm and unity-current-gain cutoff frequency f_t of 50 GHz. The uniformity of g_m was better than 1%, and the voltage of the g_m peak was uniform to ±30 mV. HIGFETs with L_g=0.3 μm showed f₁ up to 63 GHz, but suffered from serious short-channel effect, due to excessive thickness of the InGaAs channel layer. A self-aligned technique for gate resistance reduction is shown to substantially improve microwave power gain     

Backgating studies inIn0.53Ga0.47As/In0.52Al0.48As modulation-doped field-effect transistors

A study is presented of the backgating effects in normal and inverted modulation-doped field-effect transistors (MODFETs) grown by molecular-beam epitaxy and their dependence on material properties and device geometry. The experiments were performed on devices with 2-μm gate lengths. The effects of both positive and negative (with respect to the source of the experimental devices) voltages applied to both ohmic and Schottky side contacts were investigated. The inverted MODFET structures, which have a very-high-resistance InAlAs buffer layer, showed negligible backgating characteristics up to side-contact voltages as high as 50 V. The normal structures, on the other hand, were very sensitive to the side-contact voltages with essentially a zero threshold voltage     

Rapid isothermal annealing of high- and low-energy ion-implantedInP and In0.53Ga0.47As

Rapid isothermal annealing (RIA) was performed on 0.5-16-MeV Si ⁺, 1-MeV Be⁺, and 150-keV Ge⁺ implanted InP:Fe and 380-keV Fe⁺ implanted InGaAs. Annealings were performed in the temperature range 800-925°C using an InP proximity wafer in addition to the Si₃N₄ dielectric cap. Dopant activations close to 100% were obtained for 3×10¹⁴ cm^-2 Si⁺ and 2×10¹⁴ cm^-2 Be⁺ implants in InP:Fe. For the elevated temperature (200°C) 1×10¹⁴ cm^-2 Ge⁺ implant, a maximum of 50% activation was obtained. No redistribution of dopant was observed for Si and Ge implants due to annealing. However, redistribution of dopant was seen for Be and Fe implants due to annealing. Phosphorous coimplantation has helped to eliminate the Be in-diffusion problem in InP, but did not help to reduce Fe in-diffusion and redistribution in InGaAs. Using an RIA cycle with low temperature and short duration is the only solution to minimize Fe redistribution in InGaAs     

Electron transport in 0.15-μm gate In0.52Al0.48As/In0.53Ga0.47As HEMT

Magneto-transport and cyclotron resonance measurements were made to determine directly the density, mobility, and the effective mass of the charge carriers in a high-performance 0.15-μm gate In_0.52 Al_0.48As/In_0.53Ga_0.47As high-electron-mobility transistor (HEMT) at low temperatures. At the gate voltage V_G=0 V, the carrier density n _g under the gate is 9×10¹¹ cm^-2, while outside of the gate region n_g=2.1×10¹² cm^-2. The mobility under the gate at 4.2 K is as low as 400 cm²/V-s when V_G<0.1 V and rapidly approaches 11000 cm²/V-s when V_G>0.1 V. The existence of this high mobility threshold is crucial to the operation of the device and sets its high-performance region in V_G>0.1 V     

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