Heterostructure planar InGaAs/InP avalanche photodiodes, which consist of a vapor-phase epitaxial InP avalanche multiplying layer and a liquid-phase epitaxial In
0.53Ga
0.47As optical absorption layer, were fabricated. Dark current, multiplication, spectral response, and pulse response characteristics are reported. Diodes were prepared by InGaAs liquid-phase epitaxy on an InP substrate, followed by InP vapor-phase epitaxy. The vapor-phase epitaxy was adopted in the InP growth to avoid ternary layer melting encountered in the liquid-phase process. Cd diffusion was carried out in the InP layer to form a p-n junction. A uniform multiplication factor of 5.5 was observed without a guard ring. The quantum efficiency was 70 percent in the

m wavelength region without antireflection coating. Dark current density was as low as

A/cm
2at 90 percent of breakdown voltage. A fast rise time of 100 ps was observed.