InGaAs Ternary Substrates Research Articles

High-Characteristic-Temperature 1.3-$\mu$m-Band Laser on an InGaAs Ternary Substrate Grown by the Traveling Liquidus-Zone Method

We have developed high-performance 1.3-mum-band laser diodes on an InGaAs ternary substrate with a low indium content (In:0.1) grown by a novel bulk crystal growth technique called the traveling liquidus-zone (TLZ) method. This laser has a long-wavelength lasing of 1.28 mum and provides lasing operation up to 195degC by using a highly strained InGaAs quantum well. The characteristic temperatures are 130 K from 25 to 95degC and 95 K from 95 to 155degC. We investigated junction heating by comparing the lasing wavelengths for pulsed and continuous-wave (CW) operation. And, we showed the possibility of realizing a high-performance laser on an InGaAs ternary substrate.

Lattice-matched In xGa 1− xAs/In xAl 1− xAs quantum wells ( x= 0.18 and 0.19) grown on (4 1 1)A- and (1 0 0)-oriented InGaAs ternary substrates by molecular beam epitaxy

High-optical quality lattice-matched In x Ga 1− x As/In x Al 1− x As quantum wells (QWs) with indium contents of x=0.18–0.19 have been successfully grown on (4 1 1)A- and (1 0 0)-oriented InGaAs ternary substrates by molecular beam epitaxy. Strong photoluminescence (PL) with a narrow linewidth was observed from both (4 1 1)A and (1 0 0) QWs at 12 K. The peak energy of PL from QWs had a good correlation with the calculated exciton emission energy based on the band parameter of the InGaAs well layers and InAlAs barrier layers. The result indicates that the (4 1 1)A and (1 0 0) InGaAs/InAlAs QWs on InGaAs ternary substrates have 0.2 eV larger energy gap difference between their well and barrier materials than GaAs/AlAs QWs on GaAs binary substrates or InGaAs/InAlAs QWs on InP binary substrates. In addition, the (4 1 1)A In 0.18Ga 0.82As/In 0.18Al 0.82As QWs had a narrower PL linewidth than (1 0 0) QWs indicating that smoother interfaces were realized in the (4 1 1)A QWs.

Long-wavelength strained quantum-well lasers oscillating up to 210/spl deg/C on InGaAs ternary substrates

Long-wavelength InGaAs-InAlGaAs strained quantum-well lasers have been fabricated on In/sub 0.22/Ga/sub 0.78/As ternary substrates grown by the Bridgman method. The threshold current density and lasing wavelength at 20/spl deg/C are 245 A/cm/sup 2/ and 1.226 /spl mu/m, respectively. The device has lased up to 210/spl deg/C, which is the highest operating temperature ever reported for long-wavelength semiconductor lasers. The temperature sensitivity of the slope efficiency between 20/spl deg/C and 120/spl deg/C is only -0.0051 dB/K, showing suppressed carrier overflow owing to deep potential quantum wells. These high-temperature durabilities of this laser are fascinating features for application to optical subscriber and optical interconnection systems.

Calculated performances of 1.3-μm vertical-cavity surface-emitting lasers on InGaAs ternary substrates

1.3-/spl mu/m vertical-cavity surface-emitting lasers (VCSEL's) on InGaAs ternary substrates are proposed and designed, It is shown that a deep potential well on the ternary substrate enlarges optical gain of a strained quantum well in the wavelength region of 1.3 /spl mu/m. A higher reflectivity distributed Bragg reflector (DBR) is also obtained by the use of the ternary substrate because materials with a large refractive-index difference can be used for the DBR. Calculated threshold current density of 1.3-/spl mu/m VCSEL's on the ternary substrates is much lower than those on the conventional InP substrates. The possibility of extremely low threshold current density below 200 A/cm/sup 2/ and temperature-insensitive operation are described.

High T0 (140 K) and low-threshold long-wavelength strained quantum well lasers on InGaAs ternary substrates

Strained quantum well lasers emitting in the 1.2 µm region have been fabricated on In0.22Ga0.78As ternary substrates. The threshold current density of the laser with highly reflective facets is 176 A/cm2 at 20°C. The characteristic temperature (T0) of the device has reached 140 K, which is the highest value ever reported for long-wavelength semiconductor lasers.

Fabrication of high power InGaAs/AlInGaAs strained SQW lasers on InGaAs ternary substrates

High quality In0.03Ga0.97As ternary substrates have been fabricated by the liquid encapsulated Czochralski (LEC) technique using a semi-infinite melt approach. Lasers using the AlInGaAs/InGaAs alloy system have been fabricated on the conducting substrates for the first time. Pulsed powers of 16.2 W at 40 A have been recorded for devices emitting at 1.035 µm. Threshold current densities were 595 Acm-2 and the characteristic temperatures were 100 K. These data demonstrate the commercial potential of ternary substrate manufacture.

Analysis of temperature dependent optical gain of strained quantum well taking account of carriers in the SCH layer

The temperature dependence of optical gain in strained quantum well is analyzed taking account of carriers in the separate confinement heterostructure (SCH) layer. Taking account of these carriers in the SCH layer can explain to a considerable extent the difference in the temperature performance between the /spl lambda/=0.98 μm laser and /spl lambda/=1.3 μm laser. It is shown that well depth plays a crucial role for the temperature dependence of optical gain. A strained quantum well on an InGaAs ternary substrate is shown to give a high gain with a small temperature dependence.

Theoretical gain of strained quantum well grown on an InGaAs ternary substrate

Optical gain is calculated for a strained quantum well grown on a ternary In1−xGaxAs substrate which is now being developed. Using an In0.26Ga0.74As substrate we can design a strained quantum well for 1.3 μm laser with a large band gap InGaP or InGaAsP barrier layer. This gives a much deeper potential well when compared with that on an InP substrate and results in a high optical gain owing to the large subband energy separation provided by the deep well. The optical gain of the strained quantum well on the ternary substrate is shown to be higher by about 750 cm−1 when compared with that on an InP substrate.