To build three-dimensional micro-opto-electro-mechanical systems (MOEMS), new materials have to be designed. However, increased manufacturability results generally in modified/degraded optical, mechanical, and electrical characteristics. The paper presents a detailed analysis of p + silicon as an opto-electro-mechanical material for microresonators, and gives some hints on the problems associated with the use of low-temperature dielectric in electrostatic microactuators. All the relevant parameters of p + silicon are experimentally determined and process recommendations allowing improved quality are formulated. Charge injection and trapping in low-temperature dielectric are analyzed and their impact on the behavior of the electrostatic actuators evaluated.