Kenji Shimoyama

Novel Selective Area Growth of AIGaAs and AIAs with HCI Gas by MOVPE

Abstract Selective area growth of AlGaAs and AlAs was successfully demonstrated in the conventional MOVPE (TMG/TMA/ AsH 3 /H 2 ) system by introducing a small quantity of HCl gas during the epitaxial growth. Highly selective epitaxy (HSE) for Al x Ga 1−x As with high Al composition, even for AlAs, was achieved using wide passivation masks (∼ 200 μm). The effective role of HCl in the HSE of AlAs can be explained by an suppression effect of reaction between the Al containing species and mask material. The growth of AlGaAs with or without HCl gas was studied over the temperature range of 500–800°C on unmasked substrates. The new method called HSE has provided good surface morphology and excellent uniformity of thickness and Al composition. The electrical and optical characteristics of epitaxially grown layers by the HSE method were essentially the same as those of the conventionally grown layers.

A new selective MOVPE regrowth process utilizing in-situ vapor phase etching for optoelectronic integrated circuits

Abstract We describe a new selective MOVPE regrowth technique combined with an in-situ vapor phase mesa-etching process and its application for the fabrication of transverse-junction buried hetero-structures. This new technique is very useful in obtaining a clean regrowth interface even if the regrowth is on AlGaAs. We have demonstrated an optoelectronic AlGaAs/GaAs hetero-transverse-junction semiconductor device fabricated by this regrowth process. The device operates as not only a laser with a threshold current of 19 mA at room temperature but also as a junction field effect transistor with a transconductance of 120 mS/mm (6.0 μm wide active region and 200 μm long cavity).

Transverse junction buried heterostructure (TJ-BH) laser diode grown by MOVPE

Abstract The sucessful application of a MOVPE growth method instead of the LPE method to fabricate a transverse junction buried heterostructure (TJ-BH) laser diode (LD) has been achieved in an attempt to improve the characteristics of this type of LD over LDs produced by the LPE method. Laser diodes fabricated by MOVPE/LPE hybrid processes have shown sufficiently good characteristics ( I th =3.5 mA, C =0.5 pF. to make up for the disadvantages of LPE, e.g. difficulties in control and uniformity over large areas, an MOVPE selective regrowth method was examined. Laser diodes grown by an entire MOVPE with in-situ HCI vapor phase etching have been successful in pulse oscillation at room temperature ( I th =37mA).

Facet growth of AlxGa1-xAs with HCl gas by metalorganic vapor phase epitaxy

Abstract Facet growth of Al x Ga 1-x As over the entire range of Al composition with SiN x masks was successfully performed using low-pressure metalorganic vapor phase epitaxy (MOVPE). In this study, a small quantity of HCl gas was introduced into the MOVPE reactor during the selective growth in order to attain perfect selectivity. The facet shapes at the edges of the selectivity grown Al x Ga 1-x As stripes were little affected by the mask-to-window area ratio. The shape of the [0 1 1] oriented stripes was strongly affected by the Al composition. For the side facet of [0 1 1] oriented stripes with Ga-rich compositions, clear {111}A was obtained and side facet growth on {111}A plane was observed for Al-rich compositions. The side facet shape of [0 1 1] oriented AlAs stripes was strikingly influenced by changing V/III or HCl/III. On the other hand, the side facet of [011] oriented stripes was essentially {111}B for the whole Al composition. These results are discussed by considering a simple nucleation model, surface diffusion lengths of Group III atoms and production ofmetal chlorides.

Model for in-situ etching and selective epitaxy of AlxGa1-xAs with HCI gas by metalorganic vapor phase epitaxy

Abstract In-situ etching and selective epitaxy of Al x Ga 1-x As by introducing a small amount of HCl gas were carried out by low-pressure metalorganic vapor phase epitaxy (MOVPE). A thermodynamic model based on the equilibrium state is presented to explain the etch and growth rates. These results show that the reaction between gas phase and surface is in quasi-equilibrium. An increase in material migration length on the surface caused by introducing HCl gas is thought to be the main reason for improvement in selective epitaxy.

Fabrication of AlxGa1−xAs buried heterostructure laser diodes by in-situ gas etching and selective-area metalorganic vapor phase epitaxy

Abstract This paper presents the first successful fabrication of an AlxGa1-xAs buried heterostructure laser diode (BH-LD) entirely by metalorganic vapor phase epitaxy (MOVPE) without using the wet etching process. The BH-LDs were fabricated by the selective area etching and regrowth (SER) method, combining an in-situ HCl gas etching with a highly selective epitaxy (HSE). These devices operated in a single mode up to 35 mW CW output power. The threshold current was 10.7 mA at 25°C and the difference of the threshold current between 25°C and 60°C was as low as 3.5 mA.

Growth of (AlIn)P/GaAs single quantum well structure on (001) GaAs by gas source MBE using AsH3 and PH3 gas

Abstract Observation of photoluminescence at 4.2 K from a lattice-matched (AlIn)P/GaAs single quantum well (SQW) structure grown by gas source MBE was reported for the first time. In this MBE system, a high pressure gas cell of AsH 3 and PH 3 was introduced as a gaseous source for group V. A procedure for switching the group III and V materials is attempted to make the designed SQW structure. As a result, each distinct luminescence peak from all the wells has been observed.

Fabrication of quantum wire structures by in-situ gas etching and selective-area metalorganic vapor phase epitaxy regrowth

GaAs quantum wires (QWIs) buried on a V-shaped groove were successfully fabricated by the selective-area in-situ gas etching and regrowth processes in the metalorganic vapor phase epitaxy (MOVPE) reactor. The V-shaped groove formation by in-situ HCl gas etching and the behavior of selective growth in the V-groove were investigated. From the detail study, it was found that the AlGaAs-based quantum wires for the entire range of Al composition can be fabricated by the in-situ fabrication technique with high controllability. Clear photoluminescence peak from an arrowhead-shaped GaAs QWI completely surrounded by Al 0.5 Ga 0.5 As was obtained even at room temperature, indicating that the in-situ etching/regrowth processes are a very promising technique for realizing high performance nanostructure devices such as QWIs

Selective epitaxial growth of In1-xAlxAs by metal-organic vapour-phase epitaxy

Abstract Highly selective epitaxy (HSE) of AlAs, In 1−x Al x As and InAs has been successfully demonstrated for wide (about 200 μm) passivation masks by introducing a small quatity of HCl gas into a conventional metal-organic vapour-phase epitaxy process. We have used two thermodynamic models to evaluate the role of HCl gas in achieving high selectivity. Two factors leading to the improvement in selectivity caused by the introduction of HCl gas were considered: (1) reduction of gas-phase supersaturation of growth species; (2) inhibition of the reaction between the growth species and the mask. It is thought that the inhibition of the surface reaction results from termination of the dangling bonds on the SiNx surface by Cl and H and the inhibition enhances the surface diffusion. The effective role of HCl in the HSE of Al-containing compounds can be explained by this inhibition effect.