A method for manufacturing a semiconductor device is provided. A method of making a graphene base transistor with reduced collector area comprising forming an electron injection region, forming an electron collection region, and forming a base region. The speed of the fan may be compared to RPM values fitted on a desired curve that is representative of the Temperature-versus-RPM function for the controlled fan. A modular hub is provided that includes a set of fixed plates arranged in a circle and a set of adjustable plates that are connected to the fixed plates.