Photoionization spectroscopy, or photocapacitance, measures the capacitance as the wavelength of light illuminating the
semiconductor is scanned from low to high energy. When a threshold energy is reached for optical emission of a trapped charge
from a defect, a change is measured in the capacitance. Measurements are made at low temperature to limit the thermal emission
from traps. The manual describes each of the steps involved in preparing the sample for maximum signal.
Among the various methods offered by Semetrol, Photocapacitance is one of the most direct to interpret. The equipment
uses many of the core components as the DLTS system, such as the cryostat, vacuum pump, temperature controller. External optics
are all computer controlled, covering a range from infrared to ultraviolet: 2 μm to 300 nm.
