We propose to develop a new kind of photon detectors based on the photo-induced stress in semiconductor microcantilevers. We will measure the photo-induced stress for various semiconductor materials as a function of a number of parameters such as microcantilever geometry (length, width, thickness), input radiant power, and modulation frequency of input radiant power. This information will allow us to demonstrate the ability of microcantilever photon detectors to sense IR radiation with high sensitivity (D* > 10(11) cm Hz(1/2) W(-1)) and fast response times (<10(-6) s) based on the novel concept described in this proposal. The proposed IR photon detector has the following benefits compared to other IR detectors: (i) no cryogenic cooling, (ii) fast response times, (iii) high sensitivity, (iv) no need for thermal isolation, and (v) low cost due to established monolithic IC fabrication compatibility