We discuss the design and growth considerations of a resonant-cavity separate-absorption-and-multiplication avalanche photodiode and the effects of misfit dislocations that originate in the lattice-mismatched absorption layer. This device is grown on a GaAs substrate using molecular beam epitaxy and is designed to detect light near wavelengths of 900 nm. Such photodetectors have exhibited the following characteristics : an external quantum efficiency of nearly 80%, a spectral linewidth of less than 8 nm, an avalanche gain in excess of 40, and low dark current. In addition, a low excess noise factor corresponding to 0.2 less than or equal to k less than or equal to 0.3 has been achieved.