Basic knowledge of high brightness LED testing

Forward Voltage Testing
Understanding how new building block materials such as graphene, carbon nanotubes[1], silicon nanowires[2] or quantum dots will function in future electronic devices requires the use of instrumentation techniques that can measure resistance, resistivity, mobility and conductivity over a wide range. This often requires measurements of very low currents[3] and voltages. The ability to make accurate and repeatable measurements at the nanometer scale is critical to engineers seeking to develop and commercialize these next-generation materials. Optical
 
Testing
Forward current bias[4] is also required for optical measurements because current is closely related to the amount of light emitted by the HBLED. The emitted photons can be captured using a photodiode or integrating sphere, allowing the optical power to be measured. The light emission can be converted to a current and measured using an ammeter or a single channel of a source-measure unit.
 
Reverse Breakdown Voltage Testing
The reverse breakdown voltage[5] (VR) can be measured by applying a reverse bias current to the HBLED. The test current should be set so that the measured voltage value no longer rises significantly with a slight increase in current. At higher voltages, the change in reverse voltage caused by a large increase in reverse bias current is not significant. The VR test method is to output a low reverse bias current for a specific period of time and then measure the voltage drop across the HBLED. The result is generally tens of volts.