Toshihiro Kusunoki

Observation of etch pits produced in InP by new etchants

Abstract New etchants, HBr/HF or HBr/CH 3 COOH, produced sharp etch pits on (100) and (111) slices of InP. The etch pit shape produced on (100) by HBr/HF was pyramidal. The shape on (100) produced by HBr/CH 3 COOH varied from pyramidal to elongated rectangular along 〈110〉 with increasing the composition ratio of CH 3 COOH to HBr. The shape produced on (111)B by HBr/HF or HBr/CH 3 COOH was triangular pyramidal. The etch rates of these new etchants and HBr/H 3 PO 4 were measured as a function of composition ratio at room temperature. The correspondence between pits and dislocations was examined and the results indicated that etch pits produced by these etchants corresponded to dislocations.

Growth of ternary InxGa1−xAs bulk crystals with a uniform composition through supply of GaAs

Ternary In0.14Ga0.86As bulk crystals with a uniform composition were found to be grown at a constant temperature by continuously supplying the depleted solute elements of Ga and As to the growth melt. The pseudo-binary InAs-GaAs melts were used as the growth melts. Compositionally graded 〈111B〉 InxGa1−xAs (0.05 ≤ x ≤ 0.08) crystals were used as seed crystals. The liquid encapsulated Czochralski (LEC) technique with a method of supplying GaAs source material was used to grow the ternary bulk crystals. Polycrystalline GaAs was used as a source material. A 4 mm thick and uniform In0.14Ga0.86As single crystal was obtained.

Multicomponent zone melting growth of ternary InGaAs bulk crystal

InxGa1-x As crystals with x = 0.25-0.08 have been successfully grown on GaAs seeds by a method of multicomponent zone melting growth. Its alloy composition is found to be controlled by the growth temperature. Within an ingot, a good uniformity in the alloy composition along the direction normal to the growth is also achieved. The alloy composition gradually changes along the growth direction in the ingot, and this change is well explained by a temperature profile in the growth furnace.

Constant temperature LEC growth of InGaAs ternary bulk crystals using the double crucible method

A double crucible method was developed to improve the controllability of the supply of GaAs source element to the growth melt close to the growing interface for the liquid encapsulated Czochralski (LEC) technique. The double crucible has growth melt and source melt zones which are separated by a cylindrical wall with a slit. The GaAs solute element is controllably supplied from the source melt zone. The GaAs constituent is supplied to the source melt by immersing a GaAs source rod in the source melt zone. An In0.07Ga0.93As uniform crystal can be successfully grown using this method. The length and diameter of the crystal are about 5 and 1.5 cm, respectively.

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.

Fabrication of In/sub 0.25/Ga/sub 0.75/As/InGaAsP strained SQW lasers on In/sub 0.05/Ga/sub 0.95/As ternary substrate

A uniform In/sub 0.05/Ga/sub 0.95/As ternary substrate was grown by using liquid encapsulated Czochralski (LEC) technique with a method of supplying GaAs source material at a constant temperature, and InGaAs/InGaAsP strained single quantum well (SQW) lasers were fabricated on the substrate for the first time. The lasers lased at 1.03 /spl mu/m and exhibited low threshold current density of 222 A/cm/sup 2/ and excellent characteristic temperature of 221 K, showing that the ternary substrate has a sufficient quality for laser fabrication.<<ETX>>

LEC growth of InGaAs bulk crystal fed with a GaAs source

Abstract In x Ga 1− x As ( x = 0.055 ± 0.004) bulk single crystals were grown by LEC while being fed with a GaAs source. To control the diameter and composition, a new crucible consisting of two melt reservoirs was used. The InGaAs crystal was grown in one melt reservoir and the source material was immersed in another reservoir. We confirmed that a homogeneous crystal with larger diameter than that of the seed can be obtained by growing at a constant temperature while dissolving sufficient GaAs source in the melt solution.

Growth of ternary In0.14Ga0.86As bulk crystal with uniform composition at constant temperature through GaAs supply

In using the liquid encapsulated Czochralski (LEC) technique, ternary In0.14Ga0.86As bulk crystals with uniform composition were grown at a constant temperature by successively supplying GaAs of the depleted solute component to the growth melt. The LEC technique with a supplying mechanism of GaAs source material was used to grow the ternary bulk crystal. A 4 mm long single bulk In0.14Ga0.86As crystal was obtained. Compositionally graded InxGa1-xAs (0.05<x<0.08) crystals were used as seed crystals. The seed crystals were prepared by using conventional LEC growth in which both the cooling rate and the pulling speed were optimized.

Compositional variation in Si-rich SiGe single crystals grown by multi-component zone melting method using Si seed and source crystals

The effect of the supply of depleted Si solute elements on the compositional variation in the Si-rich SiGe bulk crystals was studied using the method which was used to grow Ge-rich SiGe single crystals with a uniform composition. By selecting the proper pulling rate, we can obtain Si-rich Si1−xGex bulk crystals with uniform composition of x=0.1 without using the supply mechanism of depleted Si solute elements. When the supply mechanism of Si solute elements was used, the initial composition in Si-rich SiGe crystals can be much more easily determined by controlling the growth temperature than that in Ge-rich crystals because the Si seed crystal is not melted down. The supply of Si solute elements is very effective to change the compositional variation even for Si-rich SiGe crystals.

Bridgman growth of compositionally graded InxGa1 − xAs (x = 0.05−0.30) single crystals for use as seeds for In0.25Ga0.75As crystal growth

Abstract We have succeeded in growing compositionally graded In x Ga 1 − x As ( x = 0.05−0.30) single bulk crystals by the Bridgman method. These graded crystals can be used as InGaAs seed crystal on which In 0.25 Ga 0.75 As bulk crystal can be grown under lattice-matched condition. In this method, InAs and GaAs binary crystals were used to make initial ternary growth melt. The control of the pulling rate or the growth rate was the most important factor in obtaining the single graded crystals with high In content. The size of the grown single crystals is 1.5 cm long with diameter 1.5 cm.