Yutaka Mihashi

Long-Wavelength Receiver Optoelectronic Integrated Circuit on 3-Inch-Diameter GaAs Substrate Grown by InP-on-GaAs Heteroepitaxy.

A monolithic long-wavelength receiver optoelectronic integrated circuit (OEIC), which integrates an InGaAs PIN-photodiode (PD) and a GaAs field-effect transistor (FET), has been successfully fabricated on a 3-inch-diameter GaAs substrate using InP-on-GaAs heteroepitaxy, by metalorganic chemical vapor deposition (MOCVD) and conventional GaAs-IC process technology. The epitaxial quality of the PD layer has been improved by use of a low-temperature-grown buffer layer, thermal cyclic annealing and an InGaAs/InP strained-layer superlattice. The integrated PD has low dark current of 10 nA at -5 V bias voltage, and exhibited stable operation at 175°C. The fabricated receiver OEIC has 1.4 GHz bandwidth and sensitivity of -28.1 dBm at the transmission rate of 622 Mb/s with bit error rate of 10-9, which is applicable to practical subscriber optical communication systems.

1.3 /spl mu/m uncooled AlGaInAs-MQW DFB laser with /spl lambda//4-shifted grating

1.3 /spl mu/m uncooled AlGaInAs DFB-LDs with /spl lambda//4shifted grating have been successfully demonstrated. Relaxation oscillation frequency as high as 11.5 GHz has been obtained. Clear opening in the eye diagram under 10 Gbps direct modulation at 75/spl deg/C has been also confirmed. Preliminary life test over 5000 hours with no failure indicates its excellent reliability. The 1.3 /spl mu/m AlGaInAs DFB-LD with /spl lambda//4-shift grating is promising for the next generation high-speed data link systems such as 10 Gbps Ethernet.

Zn-Diffusion-Induced Disordering of InGaAs/AlGaInAs Multiple Quantum Well and Its Application to Long-Wavelength Laser

Zn-diffusion-induced disordering of the InGaAs/AlGaInAs multiple quantum well (MQW) is investigated as a new processing technique for long-wavelength optoelectronic devices. Complete disordering of the MQW structure is confirmed through the observation of the shortening of the photoluminescence peak wavelength and secondary ion mass spectroscopy (SIMS) measurement. Lattice-matched disordering is also confirmed with X-ray diffraction. A long-wavelength buried-MQW laser is fabricated for the first time, in which index-waveguide and carrier confinement are obtained by disordering. The pulsed oscillation at room temperature is achieved near 1.56 µ m.

Highly reliable 1.3 μm AlGaInAs FP lasers with low power penalty under uncooled 10Gbps operation at 85°C

We have realized highly reliable 1.3 μ m AlGaInAs FP lasers with low power penalty of 1.4dB at 10Gbps and 85°C. The MTTF was estimated over 1.5×105 hours and no deterioration of COD level was observed during the life test.

Transverse mode control in wide-single-stripe lasers by loading modal filters

Preliminary studies demonstrate the effectiveness of modal filters for controlling transverse modes in wide-single-stripe SBA (self-aligned bent-active-layer) lasers by means of two methods. The first uses a flared waveguide SBA laser while the other uses a wide-stripe SBA laser with a modal reflector at the output facet. Both lasers demonstrate single-lobed far-field patterns. These preliminary experiments show that both modal filters are effective for transverse-mode control. Higher output power in the fundamental transverse mode can be attained by combining these two modal filters.<<ETX>>

Thermosenstor &#8212; A new temperature-sensitive switching device

A new type of temperature-sensitive switching device constructed with a p-n-p -n structure has been developed. This new device can be turned on by a predetermined temperature under the forward bias. This turn-on temperature can be shifted from 50°C to 150°C by connecting gate shunt resistance in parallel with emitter junction of the device. This device owes its features to the thyristor structure which gives contactless and latching switch, gate controlled operation and fast switching. However, several modifications have been made from conventional thyristor design in doping levels and dimensions for temperature-sensitive switching device. The structure, operation, characteristics the feature of the device are described.

In-situ monitoring of AlGaInP by reflectance spectroscopy in metalorganic vapor phase epitaxy

We have investigated a real-time reflectance spectroscopy during AlGaInP growth by metalorganic vapor phase epitaxy. The analysis of Fabry-Perot oscillation gives the optical parameters of epitaxial layer such as refractive index (n) and extinction coefficient (k). By using the relationship between these optical parameters and the composition of AlGaInP, in-situ monitoring of growth rate (R/sub g/) and Al content x in (Al/sub x/Ga1-x)/sub 0.51/In/sub 0.49/P is realized without any dependence on the structure. R/sub g/ and Al content x estimated by using this in-situ monitoring method are in good agreement with those obtained by conventional measurement such as thickness, XRD and PL spectroscopy.

High speed 1.3 /spl mu/m AlGaInAs DFB-LD with /spl lambda//4-shift grating

1.3 /spl mu/m AlGaInAs DFB-LD with /spl lambda//4-shift grating has been developed for the first time. The light output power over 5 mW at 85/spl deg/C has been obtained for the DFB-LD. Relaxation oscillation frequency (fr) as high as 11.2 GHz@5 mW at a negative detuning of -10 nm has been attained. Clearly opened eye diagram at 10 Gbps modulation has been also confirmed at 75/spl deg/C, which demonstrate excellent transmission characteristics. Stable operation over 1700 hours at 10 mW@85/spl deg/C in the preliminary life test has been confirmed.

Planar selective re-growth around a dry-etched mesa along the [11~0] direction by addition of HCl during MOCVD growth

We have investigated the selective MOCVD re-growth of InP aroundnmesa-stripes along [11¯0] direction formed with reactive ionnetching by the addition of HCl gas during MOCVD growth. It is shown thatnthe large overgrowth on the SiO 2 mask in the conventionalngrowth condition is remarkably reduced by the addition of the HCl gas.nThe mechanism of this effect is analyzed experimentally. It is foundnthat the growth rate on (110) plane (mesa side wall) decreases morenremarkably than that on the (001) plane (mesa base) with increasing HClnflow rate. Therefore the growth rate on the side wall can be effectivelynreduced by the addition of adequate amount of HCl. The reduction of thengrowth rate on the (110) plane suppress the formation of (111)A plane,nwhich is the cause of the large overgrowth near the mask edge of thenmesa stripes. Using these results, we have successfully achieved planarnembedded re-growth of InP around dry-etched mesa along [11¯0]ndirection. This technique is very useful in the application of selectivenMOCVD growth to the photonic integrated circuits

Temperature-sensitive switching device thermosenstor

A p-n-p-n temperature-sensitive switching device Thermosenstor operatable in the temperature range of -30°C to 150°C has been developed by implanting argon ion to the collector junction of the p-n-p-n structure. Argon ion implantation also permits the device to be less sensitive to the dV/dt triggering as well as to eliminate the on-off switching temperature differential. The construction, characteristics and reliability are described.