In this paper

we report a multi-gradient layers （three or more） InGaAs （P）/InP avalanche photodiode with the middle bandgap transition between seperated absorp tion and multiplication regions

which has beed successfully developed by using liquid phase epitaxy growth and traditional photoetching fabrication technique （referred to as InGaAs （P）/InP SAGM）. The obtained test results are: breakdown voltage VB=40～90V

dark cur rent Idmin（0.9 VB）<10nA

responsivity （1.3μm）Re=0.6～0.8A/W

multiplication factor M ≥20（Mmax>40）

excess noise factor F=5

and wide band frequency response.