Excess noise design of InP/GaInAsP/GaInAs avalanche photodiodes

An InP/GaInAsP/GaInAs avalanche photodiode (APD) with separate absorption and multiplication (SAM) regions has been designed taking into account the excess noise generated in GaInAsP and GaInAs. The multiplication factor dependence of the excess noise factorFhas been calculated using realistic electron and hole ionization rates in InP, GaInAsP, and GaInAs, assuming that the avalanche multiplication occurs not only in InP but in GaInAsP and GaInAs. The calculatedFvalues have been compared to the experimental ones measured on a planar-type InP/GaInAsP/GaInAs APD for illumination at a wavelength of 1.3 μm. It has been found the the calculated excess noise agrees very well with the experimental measurements. The limited ranges of device parameters in which the conditions of minimal excess noise, tunneling current, and charge pile-up are satisfied have been obtained. We conclude that the excess noise generated in GaInAsP and GaInAs should be considered in a practical device design.     

Development of high-quantum-efficiency,lattice-mismatched, 1.0-eV GaInAs solar cells

High-quantum-efficiency, lattice-mismatched, 1.0-eV GaInAs solar cells grown by organometallic vapor phase epitaxy have been developed for ultimate integration into AlGaAs/GaAs/GaInAs 3-junction, 2-terminal monolithic devices. The more standard n/p junction was replaced with an n-i-p structure in the GaInAs cell in order to increase the short-circuit current by overcoming the material deficiencies which arise as a result of accommodating the lattice mismatch. This led to single junction 1.0-eV GaInAs cells with internal quantum efficiencies >90% and short-circuit-current densities that match or closely approach those needed to current match the upper AlGaAs and GaAs cells. A 4.1% (1-sun, air mass 0,25°C) power conversion efficiency was achieved with a developmental structure, indicating the potential of the lattice-mismatched n-i-p 1.0-eV GaInAs cell. An analogous device designed to allow direct monolithic integration with the upper AlGaAs and GaAs cells, with a modified grading layer of AlGaInAs in place of the usual GaInAs, achieved an efficiency of 2.2%, primarily due to a lower open-circuit voltage. The open-circuit voltage is perhaps limited by structural defects revealed in transmission electron micrographs.     

Designing of 1 eV GaNAs/GaInAs superlattice subcell in current-matched four-junction solar cell

A reasonably-thick GaNAs/GaInAs superlattice could be an option as a roughly 1 eV subcell to achieve high-efficiency multi-junction solar cells on a lattice-matched Ge substrate. A detailed consideration of a high-efficiency design for a GaInP/GaAs/1 eV/Ge device is presented. Calculations have been done for this structure to obtain the confined energies of the electrons and holes by utilizing the Kronig-Penney model, as well as the absorption coefficient and thereby the external quantum efficiency. The effect of well layers, GaNAs or GaInAs, on the absorption and photocurrent density under the AM 1.5 condition is discussed in order to realize a requirement of current matching in the four-junction solar cells. The management of these considerations implies the feasibility of the GaNAs/GaInAs superlattice subcell design to improve the overall conversion efficiency of lattice matched GaInP/GaAs/1 eV/Ge cells.     

Multi-quantum-well lasers emitting at 1.55 mu m grown by GSMBE

GaInAs/GaInAsP multi-quantum-well structures emitting at 1.55 mu m have been realised by gas source molecular beam epitaxy (GSMBE) over a large range of growth temperature. Threshold current densities as low as 0.81 kA/cm/sup 2/ have been obtained. The first BH lasers fabricated by GSMBE from these heterostructures exhibit low threshold current (18 mA) and linear DC light-current characteristics up to 20 mW.<>     

Quantum-dot microlasers

Edge-emitting short-cavity lasers with deeply-etched Bragg mirrors were fabricated on a GaInAs/AlGaAs laser structure with a single active layer of self-organised GaInAs quantum-dots. Continuous wave operation has been achieved down to cavity lengths of 16 μm with a minimum threshold current of 1.2 mA for 30 μm-long devices     

High-temperature (T=490 K) operation of 5.8 /spl mu/m quantum cascade lasers with InP/GaInAs waveguides

5.8 /spl mu/m Ga/sub 0.4/In/sub 0.6/As/Al/sub 0.56/In/sub 0.44/As strain-compensated quantum-cascade lasers with InP and GaInAs cladding layers using solid-source molecular-beam epitaxy have been fabricated. Low threshold current densities and high-temperature operation of uncoated devices, with a record value of 490 K, have been achieved in pulsed mode.     

High-performance Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As MSM-HEMT receiver OEIC grown by MOCVD on patterned InP substrates

Reports the first demonstration of a new long-wavelength receiver OEIC comprising an AlInAs/GaInAs MSM detector and an AlInAs/GaInAs HEMT preamplifier. The layer structure was grown by LP-MOCVD on patterned InP substrates, which allowed independent optimisation of the MSM detector and HEMT preamplifier. The MSM detector showed the lowest leakage current yet reported and the HEMT exhibited a transconductance of 260 mS/mm. An excellent receiver response to 1.7 Gbit/s NRZ signals has been obtained.<>     

High-power 0.98 mu m GaInAs strained quantum well lasers for Er/sup 3+/-doped fibre amplifier

High-power GaInAs strained quantum well lasers with an emission wavelength of 0.98 mu m, suitable for Er/sup 3+/-doped fibre amplifier pumping, have been fabricated. A threshold current of 15 mA and a peak output power as high as 85 mW have been obtained for the ridge waveguide structure with AR/HR facet coating. Highly efficient pumping for the 1.536 mu m signals has been confirmed.<>     

AlGaInP/GaInAs strained quantum well lasers

AlGaInP cladding layers have been applied for the first time to GaInAs strained quantum well lasers oscillating around 0.98 mu m. The device has lower threshold current and larger T/sub 0/ than a device with GaInP cladding layers. This was expected from a larger bandgap difference between active and cladding layers.<>     

High-speed monolithic GaInAs pinFET

A monolithic planar structure pin photodiode/field-effect transistor (pinFET) consisting of a low capacitance InP/GaInAs embedded pin photodiode and an AlInAs/GaInAs FET has been developed for long wavelength optical communications. Very high bitrate response capability of over 8 Gbit/s and good receiver performance at 2 Gbit/s have both been demonstrated     

Low-threshold, high-power, single-longitudinal-mode operation i 1.5μm multiple-quantum-well, distributed-feedback laser diodes

Extremely low-threshold, single-longitudinal-mode operation is reported for 1.5 μm band GaInAs multiple quantum well, distributed feedback laser diodes. A 5.5 mA minimum threshold current as well as 40 mW maximum light output power and 0.33 W/A maximum quantum efficiency have been attained under CW condition at room temperature     

Accurate modeling for parasitic source resistance intwo-dimensional electron gas field-effect transistors

An accurate two-layer model has been developed for parasitic source resistance in two-dimensional electron gas field-effect transistors (2DEGFETs). In this model, the 2DEG concentration-voltage and current density-voltage relations at the cap/barrier/2DEG junction are taken into account, based on the self-consistent charge control model and effective mass tunneling theory. Empirical 2DEG velocity field characteristics are also included. To show the feasibility of this method, the source resistance in conventional GaAs/AlGaAs 2DEGFETs was analyzed and the AlGaAs thickness dependence was discussed. For comparison, the lattice-matched GaInAs/AlInAs 2DEGFET and pseudomorphic GaInAs/AlGaAs 2DEGFET were examined. It was shown that introducing a highly doped cap layer leads to a drastic reduction in source resistance for pseudomorphic 2DEGFETs but has a very small effect for GaInAs/AlGaAs 2DEGFETs     

Ga0.47In0.53As depletion mode MISFETs withnegligible drain current drift

Ga_0.47In_0.53As depletion-mode metal insulator semiconductor field-effect transistors with a transconductance in the range 100-140 mS/mm and with no significant current drift (less than 3% in 30 hours) have been fabricated on epitaxial layers grown by MOCVD. This high performance has been achieved using an efficient passivation of the GaInAs surface which associates in situ native oxide removal by a hydrogen multipolar plasma and a Si₃N₄ film deposition     

Al0.48In0.52As/Ga0.47In0.53As resonant tunnelling diodes with large current peak/valley ratio

Resonant tunnelling diodes consisting of an MBE-grown AlInAs barrier on each side of a lattice-matched GaInAs well have been fabricated. Current peak/valley ratios up to 7.1 and 39 have been measured at 300 K and 77 K, respectively. These represent the largest values reported to date in any double-barrier, single-well device. The enhanced peak/valley ratio has been attributed to thick barriers (72 Å) and wide, undoped GaInAs spacer layers (400 Å)     

Monolithic pin-HEMT amplifier on an InP substrate grown byOMVPE for long-wavelength fibre optic communications

The authors have monolithically integrated a GaInAs pin-photodiode and an n-AlInAs/GaInAs HEMT amplifier on an InP substrate by OMVPE for long-wavelength fibre optic communications. The response of the pin-HEMT amplifiers for 1.6 Gbit/s (NRZ) signals has been obtained     

Self-aligned diffusion technique for n-InP JFETs

A self-aligned diffusion process has been demonstrated in the fabrication of n-InP JFETs on semi-insulating InP. This process utilises the anisotropic and selective etching properties of InP/GaInAs materials. Using this technique, sub-micrometre gate lengths can be achieved even with conventional photolithography. Devices with trans-conductance of >35mS/mm, leakage current of < 10nA/mm and gate capacitance of <0.7pF/mm have been fabricated with a cutoff frequency of 7 GHz.     

Gate current in AlInAs/GaInAs heterostructure insulated-gatefield-effect transistors (HIGFETs)

A self-aligned WSi gate heterostructure insulated-gate field-effect transistor (HIGFET) with a gate length of 1 μm was fabricated using an AlInAs/GaInAs heterostructure grown by atmospheric pressure metal-organic chemical vapor deposition (MOCVD). The gate current is investigated experimentally and theoretically. The measured gate current was found to be about two orders of magnitude higher than predicted by theory. The origin of this increase is unclear. However, the theoretical result suggests the possibility of reducing the gate current in AlInAs/GaInAs HIGFETs     

GaInAs metal/semiconductor/metal photodetectors with Fe:InP barrier layers grown by chemical beam epitaxy

A GaInAs metal/semiconductor/metal (MSM) photodetector with a dark current less than 1 mu A is described. An Fe-doped InP layer was introduced between the metal and the GaInAs absorbing layer to improve the Schottky barrier height. A breakdown voltage of 30 V was achieved. A DC quantum efficiency of 64% and an impulse response, 1/e fall time of 190 ps were measured for a 20 mu m*100 mu m device. The layer structure is very attractive for integration with high-performance GaInAs/InP FETs.<>     

High speed non-selfaligned InP/InGaAs Npn heterojunction bipolar transistor grown by low pressure metal organic vapour phase epitaxy

Lattice matched GaInAs/InP Npn heterojunction bipolar transistors (HBTs) have been grown by lower pressure metal organic vapour phase epitaxy (MOVPE) and precessed with non-selfaligned fabrication techniques. The transistors exhibit a cutoff frequency of 60 GHz and maximum oscillation frequency of 32 GHz which are the highest values reported to date for GaInAs/InP HBTs grown by MOVPE.<>     

MOCVD-grown AlInAs/GaInAs MODFET with drain currents higher than 1.3 mA/mm

Very high-density and high-mobility AlInAs/GaInAs modulation-doped heterostructures have been successfully grown by low-pressure MOCVD. FETs, having gate-lengths of 0.25 mu m, fabricated from these heterostructures show transconductances as high as 700 mS/mm, and drain saturation currents in excess of 1.3 mA/mm at V/sub gs/=0 V. This current density is among the highest yet reported for FETs grown by any technique. The extracted current-gain cutoff frequency is 78 GHz.<>