High quality unintentionally doped InP

quaternary alloy Ga

x

In

1-x

As

y

P

1-y

epilayers and the distributed Bragg reflectors(DBRs) formed alternately with high and low refractive index semiconductor materials have been grown on InP substrates in an atmospheric or low pressure metal organic chemical vapor deposition system made up in our laboratory.The trimethylindium(TMIn)

trimethylgallium (TMGa)

arsine(AsH

3

) and phosphine(pH

3

) are as the source materials.The properties of the epilayers were investigated by measurement of X-ray diffraction

X-ray rocking curve

scanning electronic microscope

low-temperature photoluminescence spectra in detail.The results indicated that the Ga

x

In

1-x

As

y

P

1-y

quaternary alloys epilayers grown by LP-MOCVD have good lattice match to InP substrates.The lattice mismatch is only 1×10

-3

between Ga

x

In

1-x

As

y

P

1-y

epilayers and InP substrates.And we obtained the InP and Ga

x

In

1-x

As

y

P

1-y

epilayers with better optical quality.The FWHM of PL spectrum of the Ga

x

In

1-x

As

y

P

1-y

epilayers and InP epilayers were 32

9.3meV

respectively.The results measured by SEM indicated that we successfully obtained high quality DBR structures.They are formed by laying down alternating layers of Ga

x

In

1-x

As

y

P

1-y

and InP semiconductors materials with different refractive index.The optical thickness of each layer of alternating growth layers is λ/4n (0.1μm).λ is the center wavelength

n

is the refractive index of each alternating growth layer.Although when the number of alternating layers is 23

the reflectivity of the DBRs layers will reach 90%

but more epilayer will increase the resistance of the device and raise the threshold current.So it is important to optimize a suitable number of layers.