The In

0.5

(Ga

1-x

Al

x

)

0.5

P quaternary alloys has been an interesting material

because of high recombination probability

high emission efficiency

direct band-gap transition and small lattice-mismatch to GaAs substrate.Thus In

0.5

(Ga

1-x

Al

x

)

0.5

P alloys was ideal active and cladding layer material for LEDs and LDs operating in the red to green region of the visible spectrum. However

many problems plague the MOCVD growth of In

0.5

(Ga

1-x

Al

x

)

0.5

P

including oxygen and carbon contamination

due to the Al

the difficulties increases as the band-gap energy increases. The In

0.5

(Ga

1-x

Al

x

)

0.5

P materials were grown on the silicon doped GaAs substrate by LP-MOCVD.The metalorganic precursors were trimethylindium(TMIn)

trimethylgallium(TMGa)

trimethyaluminum(TMAl).The hydride source was phosphine(PH

3

).The dopant source was silane(SiH

4

) and dimethylzinc(DEZn)

respectively.Al composition in In

0.5

(Ga

1-x

Al

x

)

0.5

P epilayer was

x

=0.6. To investigate the effect of the growth conditions such as temperature

dopant flow rate

Ⅴ/Ⅲ ratio

Al composion and substrate orientations on doped concentration

the growth of doped InGaAlP alloys was studied by LP-MOCVD.We demonstrated that lowering temperature and reducing Al composion

increasing the flow rate of DEZn

and selecting the substrate inclining 6 to 15° from

<

100

>

to

<

111

>

are contribute to the increasing of Zn-doped concentration in InGaAlP alloys. While raising temperature and increasing the flow rate of SiH

4

reducing Al composion and Ⅴ/Ⅲ ratio are contribute to Si doped concentration

and the orientations of substrate has no effect on the latter.