The In

x

Ga

1-x

As material is very important for uncooled infrared detector and has spectral response from 1 μm to 3 μm. In recent years

there are growing needs for high In composition In

x

Ga

1-x

As detectors

the most important applications are spectral imaging including earth observation

remote sensing and environmental monitoring

etc. The In

x

Ga

1-x

As (x

>

0.53) was grown on semi-insulating (100) Fe-doped InP substrates by LP-MOCVD. The growth was performed using TMIn

TMGa

and AsH3 as growth precursors in a horizontal reactor. Two step method of In

0.82

Ga

0.18

As growth that the buffer layer was grown at low temperature of 450℃ and the epilayer was grown at higher temperature of 530℃ was studied. After depositing 300 nm In

x

Ga

1-x

As buffer layer

In

0.82

Ga

0.18

As epilayer with thickness of 1 μm was deposited. It was observed that the different In composition of In

x

Ga

1-x

As buffer layer influence on crystalline quality and surface morphology of In

0.82

Ga

0.18

As epilayer. The crystalline quality of the epilayer materials was characterized by X-ray diffraction (XRD). In our experiment

the In composition of the In

x

Ga

1-x

As buffer layers was 0.28

0.53

0.82 and 0.88

respectively. The full-width-at-half-maximum (FWHM) of diffraction peak for the buffer layer of In

0.82

Ga

0.18

As is 0.362° and is the narrowest among the four samples. The surface morphology was observed by scanning electron microscopy (SEM). The SEM image of the sample with buffer layer of In

0.82

Ga

0.18

As is a flat surface and is better than other samples with cross-hatches

pits or some defects. We found that the In composition of the In

x

Ga

1-x

As buffer can influence on the surface morphology of the In

0.82

Ga

0.18

As epilayer. The experiments show the crystalline quality and the surface morphology of the In

0.82

Ga

0.18

As epilayer is optimum when the In composition of buffer layer is the same as that of the epilayer.