An In0.53Ga0.47As junction field-effect transistor

Preliminary results are reported for the operation of a junction field-effect transistor fabricated from In0.53Ga0.47As grown lattice-matched to an InP:Fe substrate.     

Anomalous effects of lamp annealing in modulation-doped In0.53Ga0.47As/In0.52Al0.48As and Si-implanted In0.53Ga0.47As

The effects of pulsed halogen-lamp annealing on modulation-doped In0.53Ga0.47As/In0.52Al0.48As heterostructures and Si-implanted In0.53Ga0.47As have been studied to determine the suitabiiity of this process in the fabrication of high-performance field-effect transistors. Implantation and annealing of these materials are necessary for contact and self-aligned gate formation. Mobilities as high as 7400 cm²/ V . s are measured at 300 K in undoped molecular-beam epitaxy In-GaAs implanted with 8 × 10¹²cm^{-2 29}Si⁺and lamp annealed at 700°C for 5 s. Anomalous overactivations (up to 120 percent) are observed in these layers When silox encapsulation is used during annealing, but the effect is absent for GaAs proximity capping. Sharp decreases in sheet-electron concentration and mobility occur in the normal modulation-doped structures for annealing temperatures > 750°C, while this trend is much smaller in the inverted structures. Arsenic loss from the In-AlAs doping layer is attributed as the main mechanism for this behavior, which makes the inverted structure more suitable for device processing. Depth profiling in the modulation-doped structures indicates that there may be serious pinchoff problems in these devices when annealed at higher temperatures due to outdiffusion of impurities from the InP substrate. Values of interdiffusion coefficients at the InGaAs/ InAIAs heterointerfaces, being reported for the first time, are almost three orders higher than those measured in the GaAs/AIAs systems.     

In0.53Ga0.47As submicrometer FET's Grown by MBE

We describe the fabrication process for InGaAs submicrometer gate JFET's, using Be ion implantation and wet chemical etching. A gate length as small as 0.5 µm can be formed by this technique. Such FET's made on MBE-grown material bad a dc trans-conductance as high as 85 mS/mm and showed a high power-handling capability.     

Studies on an In0.53Ga0.47As/In0.52Al0.48As single-quantum-well quasi-MISFET

We describe here the properties of a novel InGaAs/ InAlAs quasi-MISFET in which an inverted modulation-doped single quantum well forms the channel and an undoped semi-insulating InAlAs constitutes the gate barrier. The entire structure is grown lattice-matched to InP continuously by molecular-beam epitaxy in a single step. Rapid thermal annealing of implanted semiconductors and ohmic contacts have been investigated and have been used successfully in the fabrication of the MISFET's. Improved performance is obtained with the incorporation of Ti in the source-drain metallization, with which contact resistances as low as 0.1 ω . mm are measured. Charge-control modeling of the proposed device predicts the carrier concentration in the channel region fairly well at room temperature. A quantum mechanical modeling of the device in the effective mass approximation also has been done. The thickness of the InAlAs doping layer is found to be an important parameter that controls the device turn-on characteristics. The velocity-field characteristics of the two-dimensional channel electrons were measured by pulse current-voltage and pulsed Hall techniques. The maximum velocities measured at 300 and 77 K are 1.5 × 10⁷and 1.7 × 10⁷cm/s, respectively. Fairly high electron mobilities are measured in single-quantum-well MISFET structures even with well thicknesses as small as 100 Å. The InAlAs gate barrier is effective in reducing the gate leakage current. Gate leakage currents are reduced further with a composite dielectric consisting of oxidized Al and InAlAs. An extrinsic transconductance of 310 mS/mm is measured in a 1.0-µm gate device at 300 K. A value of fT= 32 GHz, measured in a 1.0-µm device, is the best obtained so far with this material system. It is expected that submicrometer gate lengths will lead to even better performance.     

Planar type vapor-phase epitaxial In0.53Ga0.47As photodiode

A punch-through type planar photodiode with low dark current and high speed response was fabricated from low carrier density In0.53Ga0.47As grown by vapor-phase epitaxy. Dark current density was 3.1 × 10^-5A/cm²at 10 V bias. Rise time and full width at half maximum were 82 and 126 psec, respectively, at a bias above 4 V.     

In0.53Ga0.47As FET's with insulator-assisted Schottky gates

Schottky-gate FET's have been fabricated on n-type In0.53Ga0.47As using a thin interfacial silicon nitride layer between the metal and the epitaxial layer to reduce the gate leakage current. In0.53Ga0.47As was grown by molecular beam epitaxy on semi-insulating InP substrates and silicon nitride was grown by plasma-enhanced chemical vapor deposition. Devices with 1.2µm gate length and net donor doping in the mid 10¹⁶cm^-3range show dc transconductance of up to 130mS/mm. Both depletion and enhancement mode operation were observed. The effective saturation velocity of electrons in the channel is deduced to be 2.0 ± 0.5 × 10⁷cm/sec, a value 60 to 70% higher than that in GaAs MESFET's. The insulator-assisted gate technology has many advantages in fabrication flexibility and control compared with other approaches to realizing high-speed microwave and logic in FET's in In0.53Ga0.47As.     

Performance of In0.53Ga0.47As/InP avalanche photodiodes

We calculate operating characteristics of high-sensitivity high-speed In0.53Ga0.47As/InP avalanche photodiodes (APD's). We find that significant photocurrent gain is obtained for a total fixed-charge density ofsigma_{tot} > 3 times 10^{12}cm^-2in the depleted InP and0.53Ga0.47As regions. To obtain high quantum efficiency and low tunneling currents, the fixed-charge density in the InP must be in the range2 times 10^{12}cm^-2leq sigma_{B} leq 3 times 10^{12}cm^-2. We calculate the breakdown voltages for APD's with uniformly doped layers and find that practical detectors with avalanche breakdowns as low as 15 V can be realized. High quantum efficiency and fast response are obtained by compositional grading of the In0.53Ga0.47As heterointerface over a distance ofL gsim 380Å, depending on the doping and amount of the In0.53Ga0.47As layer swept out at breakdown. Finally, a comparison of calculations with experimental results is presented.     

Ion-implanted In0.53Ga0.47As/In0.52Al0.48As lateral PNP transistors

Lateral PNP transistors have been realized for the first time in the (In,Ga)As/(In,Al)As heterostructure material system. Be ion implantation has been used to form the emitter and collector junctions. A current gain of 3.8 is obtained up to 200 µA of collector current for devices with a 1.5 µm electrical base width. A hole diffusion length of 2 µm in the (In,Ga)As is estimated.     

An In0.52Al0.48As/n+-In0.53Ga0.47As MISFET with a heavily doped channel

An In0.52Al0.48As/n⁺-In0.53Ga0.47As MIS-type field-effect transistor (FET) with a channel doped at a 7 × 10¹⁷cm^-3level has been fabricated on an InP substrate. A device with a 2-µm channel length has yielded a maximum transconductance of 152 mS/mm,f_{T} = 12.4GHz, andf_{max} = 50GHz. At 10 GHz, the maximum available gain is 17.4 dB. The performance of this device shows that heavily doped channel FET's are very promising for high-frequency operation.     

A long-wavelength, annular In0.53Ga0.47As p-i-n photodetector

We describe a novel, annular In0.53Ga0.47As p-in photodiode sensitive to λ = 1.7 µm for use as a fiber tap or front-face laser monitor. The diode has a 150 µm diameter, straight-walled hole through the diode cross-section formed by photochemical etching. The hole is concentric with the 430 µm diameter mesa. A dark current of I = 90 nA at 5 V and a breakdown voltage of 33 V indicate that the hole formation process does not result in significant degradation of the device operating characteristics. Measurements of photoresponse as a function of position across the diode surface give further evidence that the hole does not effect overall device performance.     

An In0.53Ga0.47As p-channel MOSFET with plasma-grown native oxide insulated gate

We describe the operation of an In0.53Ga0.47As p-channel inversion mode MOSFET with plasma grown native oxide insulated gate. This device exhibits a transconductance of 4 mS/mm and an effective channel mobility of more than 50% of the bulk hole mobility. This device is the first demonstration of a native oxide insulated gate MOSFET in the In1-xGaxAsyP1-ymaterial system.     

Investigation of In0.53Ga0.47As for high-frequency microwave power FET's

Submicrometer In0.53Ga0.47As junction field-effect transistors (JFET's) were fabricated using a chemical etching technique. In spite of the well-known low bulk breakdown fields of InGaAs, the source-drain breakdown voltages of the FET's were close to 20 V under pinchoff conditions, indicating a potentially high power-handling capability. At 11 GHz, a 250-µm-wide FET showed a linear gain of 5.2 dB and 17.2-dB . m (53 mW) output power at 1-dB compression point, with a power-added efficiency of 14 percent. Problems of an unexpectedly low electron mobility in the channel, annealing of implanted Be, and oscillations in the drain current-voltage characteristic are discussed.     

In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As abrupt double-heterojunction bipolar transistors

In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As n-p-n abrupt double-heterojunction bipolar transistors grown by molecular beam epitaxy (MBE) have been realized for the first time. DC current gains in excess of 300 have been measured on devices operated in the emitter-up configuration. DC current gains around 50 are obtained on device structures with Be+ implanted extrinsic base regions operated in the emitter-down configuration. The carrier injection and collection behavior of the abrupt InGaAs/InAlAs heterojunctions is discussed.     

Low-noise In0.53Ga0.47As:Fe photoconductive detectors for optical communication

Photoconductive detectors were fabricated on In0.53- Ga0.47As/InP made high-resistive by doping with elemental Fe. A mobility of ∼ 6000 cm²/V . s and a net electron concentration of (2-5) × 10¹²cm^-3were measured in layers on which the devices were fabricated. Photoconductive gains of 5-10 were measured with CW and pulsed excitation. The calculation response time to 300-ps pulsed excitation is ∼ 100 ps and can be improved with reduced channel spacings. Typical dark currents in the devices are of the order of 50 µ A at room temperature. The noise power into a 50-Ω load measured at 82°C is -108.9 dBm. This is the lowest value measured in photoconductive detectors made with III-V In0.53Ga0.47As.     

Admittance measurements on In0.53Ga0.47As/InP:Fe-JFET's and GaAs-MESFET's

Admittance measurements as a function of frequency and voltage on field-effect transistor (FET) channels of In0.53Ga0.47As/InP: Fe-JFET's and GaAs-MESFET's are reported. Theoretical and experimental investigations of the conductance and susceptance show that only three independent parameters, like space-charge capacitance, series resistance, and differential resistance, are needed to describe the measured results in the entire voltage and frequency range of investigation.     

InP/In0.53Ga0.47As heterojunction phototransistors grown by chemical beam epitaxy

We describe InP/In0.53Ga0.47As heterojunction phototransistors (HPT's) grown by chemical beam epitaxy (CBE). These devices exhibit high gain ( > 150) at signal levels as low as - 50 dBm. Compared to earlier devices of this type, the gain is relatively independent of the optical signal level. This is due primarily to the improved quality of the emitter-base heterojunction interface which, for these HPT's, is characterized by an ideality factor of 1.14. At an incident power level of -21 dBm the bandwidth is 14 MHz and the gain-bandwidth product is 4.8 GHz.     

Low dark-current, high-efficiency planar In0.53Ga0.47As/InP P-I-N photodiodes

We have fabricated high quantum efficiency, high speed, low dark-current In0.53Ga0.47As/InP p-i-n planar photodiodes Which meet the performance requirements of long-wavelength optical communications systems. The diodes employ plasma deposited SiNxas a mask to Zn diffusion. The dark-current density at 10 V is J = 5 × 10^-5A/cm²with a corresponding capacitance of C = 5 × 10^-9F/cm².     

Junction field-effect transistors using In0.53Ga0.47As material grown by molecular beam epitaxy

In this article we discusss the fabrication of junction field-effect transistors (JFETs) using In0.53Ga0.47As grown p-n junction material prepared by molecular beam epitaxy (MBE). For an n-channel doping of 2 × 10¹⁶cm^-3and a gate length of 2.0µm, these devices are shown to have a transconductance of 50 mS/mm with a corresponding internal transconductance of 67 mS/mm.     

A self-aligned In0.53Ga0.47As junction field-effect transistor grown by molecular beam epitaxy

An In0.53Ga0.47As field-effect transistor has been fabricated on MBE-grown material, using a novel self-alignment technique. This device has a dc transconductance of 60 mS/mm for a 3-µm gate length, one of the highest reported figures for such a length, and a very low gate leakage of 100 nA at -3-V gate bias.     

Self-aligned In0.53Ga0.47As/semi-insulating/n+InP junction field-effect transistors

Depletion-mode junction field-effect transistors (JFET's) with InGaAs p-n junctions grown on compensated Fe:InP or highly resistive In0.52Al0.48As isolation layers grown on n⁺-InP substrates have been fabricated using a combination of molecular-beam epitaxy and metalorganic chemical vapor deposition growth techniques. Using a self-aligned gate technology with a 1-µm gate length, devices with high transconductance (80 mS/mm), low leakage current (<100 nA), and a gate-to-source capacitance of 0.4 pF have been fabricated. This is apparently the first report where InP-based alloy FET's have been fabricated on an isolated n⁺-substrate. This structure has application to monolithically integrated photoreceivers.