In this work, we model and simulate the performance of a novel InGaAs/InAlAs quantum-well metal-semiconductor-metal (MSM) photodetector at 1550-nm wavelength that utilizes recessed electrodes to access the two-dimensional (213) transport channel. Unfortunately, rather low Schottky barrier heights on undoped InGaAs lead to excessive dark currents when metal electrodes are in direct contact with this material. To remedy this situation, we propose to form barrier-enhancement regions between the optically active 2D-quantum well and the lateral 3D-metal contacts by means of ion-implantation-induced quantum-well intermixing. Simulation results indicate a reduction in dark current of nearly three orders of magnitude. Additionally, the high-speed performance appears not to be adversely affected under normal operating conditions by the potentially deleterious effects of carrier emission and accumulation at these contact heterointerfaces. The Fourier transform of a simulated transient current response to a light impulse indicates electrical 3-dB bandwidth exceeds 50 GHz in a device with a recessed electrode gap of I Pm. (C) 2004 Elsevier Ltd. All rights reserved.