An image forming apparatus including a developing device and an image carrier facing the developing device. In the reformation process and crystallization process, a heater is set at preset temperatures substantially equal to each other, and a pressure in a process chamber is set at first and second process pressures different from each other. In various embodiments, current or voltage sources generate quantum tunneling currents from the arrays of pads to biometric components using select elements as ground return paths. The source mask pattern blocks light for forming a source electrode and faces the drain mask pattern.