T. Torikai

Temperature dependence of impact ionization coefficients in InP

Impact ionization coefficients for electrons and holes in InP were measured experimentally at 25–175 °C in the 400–600 kV/cm electric field range with planar avalanche photodiodes, in which the n‐InP avalanche region was separated from the light absorbing InGaAs and/or InGaAsP layers. α and β monotonically decreased with elevated temperatures; β/α slightly decreased with increasing temperature. Comparison of the experimental results with Okuto–Crowell formula on the impact ionization coefficient gave the phonon energy ERO=46 meV and the phonon scattering mean free path λ0=41.7 A for electron impact ionization and ERO=36 meV and λ0=41.3 A for hole impact ionization, respectively. Curves calculated by using these parameters agree with the experimental results quite satisfactorily at each temperature.

Precise wavelength control for DFB laser diodes by novel corrugation delineation method

Precise wavelength control of a multiple-wavelength DFB InGaAsP strained MQW laser-diode (LD) array was achieved using weighted-dose allocation variable-pitch EB-lithography (WAVE) and highly uniform MOVPE. Multiple-wavelength 1.3 /spl mu/m /spl lambda//4-shifted DFB LD arrays with wavelength spacing of 2.0 nm were successfully demonstrated. The standard deviation of the wavelength was as low as 0.37 nm over 2-in wafers.

Impact ionization rates in

Impact ionization rates for electrons and holes in

Low threshold λ = 1.3 μm multi-quantum well laser diodes grown by metalorganic vapor phase epitaxy using tertiarybutylarsine and tertiarybutylphosphine precursors

Abstract Low threshold λ = 1.3 μm InGaAsP multi-quantum well (MQW) lasers have been realized by metalorganic vapor phase epitaxy (MOVPE) using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP). Quaternary InGaAsP growth with TBA and TBP have demonstrated an improved group-V compositional controllability, compared to that with the conventional hydrides AsH 3 and PH 3 . As a result, the base InGaAsP MQW wafers have exhibited an excellent photoluminescence (PL) wavelength uniformity with the standard deviation of 2.6 nm over a 2-inch wafer, and the PL full width at half maximum (FWHM) of 8.3 meV at 4.2 K. Laser characteristics, such as threshold and efficiency, were comparable to those grown by hydrides. The threshold currents for 70%/95% coated 170 μm long devices were as low as 9 and 22 mA at 20 and 85°C, respectively. Thus, TBA and TBP are applicable for long wavelength lasers as substitutes for AsH 3 and PH 3 .

High-speed, high-reliability planar-structure superlattice avalanche photodiodes for 10-Gb/s optical receivers

This paper reports the planar-structure InAl-GaAs-InAlAs superlattice avalanche photodiodes (SL-APDs) with a Ti-implanted guard-ring, which were developed for a compact and high-sensitivity 10-Gb/s optical receiver application. The design and fabrication of the novel concept planar-structure including the Ti-implanted guard-ring are described. The characteristics of the planar APDs are 0.36 /spl mu/A dark current at a multiplication factor of 10, 67% quantum efficiency, 110-GHz gain-bandwidth (GB) product, 15-GHz top-bandwidth, and - 27.2-dBm sensitivity at 10 Gb/s. The reliability was preliminary tested and the lifetime of longer than 10/sup 7/ h at 50/spl deg/C was estimated. The dark current characteristics including its temperature dependence and the excess noise characteristics are also analyzed. All the obtained characteristics exhibit the practical availability of the planar SL-APDs in the 10-Gb/s trunk line optical receiver uses.

Selective MOVPE growth of InGaAsP and InGaAs using TBA and TBP

Selective metalorganic vapor phase epitaxial (MOVPE) growth of InGaAs(P) using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) was systematically investigated for the first time. Selective growth was successfully achieved and the growth structure was as excellent as the structure using AsH3/PH3. Vapor phase lateral diffusion of group-III species, which is the major mechanism of selective MOVPE, can be easily controlled over the wide range of V/III ratio with using TBA/TBP. From this feature, we propose the selectively grown multiple quantum well waveguide structures which have excellent bandgap controllability by using TBA/TBP.

Monte Carlo simulation of impact ionization rates in InAlAs-InGaAs square and graded barrier superlattice

The Monte Carlo method is used to analyze impact ionization rates for electrons and holes in a crystal direction In/sub 0.52/Al/sub 0.48/As-In/sub 0.53/Ga/sub 0.47/As square and graded barrier superlattice. The calculated impact ionization rate ratio /spl alpha///spl beta/ is enhanced to more than 10 in a wide barrier and narrow-well square barrier superlattice. This is because the hole ionization rate /spl beta/ is greatly reduced in the narrower well superlattice, while the electron ionization rate /spl alpha/ is less sensitive to well and barrier layer thickness. These results are explained by a combination of the ionization dead space effect for the barrier layer and the electron ionization rate enhancement in the well layer due to large conduction band edge discontinuity. Furthermore, it is found that in a graded barrier superlattice, the impact ionization rate ratio /spl alpha///spl beta/ is smaller than that for a square barrier superlattice having the same barrier and well thickness. This is due to the occurrence of hole ionization in the narrow bandgap region in graded barriers. The band structure effects on hot carrier energy distribution, as well as impact ionization, are also discussed. >

12-channel parallel optical-fiber transmission using a low-drive current 1.3- mu m LED array and a p-i-n PD array

Twelve-channel 14-Mb/s/channel 1-km parallel optical-fiber transmission using a 1*12 low-drive-current 1.3- mu m light-emitting diode (LED) linear array and an InGaAs p-i-n photodiode linear array, with the LED drive current as low as 12 mAp-p/channel, is discussed. No receiver sensitivity degradation has been observed under simultaneous 12-channel operation. The skew was less than 6 ns after transmission through a 1-km-long 12-channel optical-fiber cable, which was sufficiently small for 14-Mb/s parallel transmission. >

Planar InP/InGaAs avalanche photodiodes with preferential lateral extended guard ring

High-speed and high-sensitivity planar InP/InGaAs avalanche photodiodes (APDs) have been fabricated with a newly developed preferential lateral extended guard ring (PLEG). By employing the configuration, avalanche photodiode yield was markedly improved without edge breakdown. Received powers required to give 10-9bit-error rate (BER) at 1.55-1.57-µm wavelength were -44.5 and -37.4 dBm for 450 Mbit/s and 2 Gbit/s, respectively.

High-power and high-efficiency photodiode with an evanescently coupled graded-index waveguide for 40 Gb/s applications

High-power evanescently coupled pin photodiodes with external efficiencies of as high as 0.96 A/W, enabled by the graded index configuration of the waveguide, have been developed for 40 Gb/s applications.