We have studied a silicon semiconductor detector as an alternative to commercial 3He-gas-basedneutron detectors. In this paper, we present a measurement of the energy spectrum of neutroninducedsecondary radiation by using a silicon detector. Polyethylene was used to produce thermalneutrons by using a 252Cf radioactive source. The photodiode was then irradiated by thermalneutrons, followed by a 10B converter that produced charged particles. This configuration wasfound to have a better response to neutrons than a moderator-converter-photodiode configuration. By comparing the measurements with Geant4 simulations, the air gap between the photodiode andthe converter was determined to be 0.3 mm and the detector response of the semiconductor devicewas found to be a smeared Gaussian function with = 0.1.