SEPARATE CONTACTLESS MEASUREMENT OF THE BULK LIFETIME AND THE SURFACE RECOMBINATION VELOCITY BY THE HARMONIC OPTICAL-GENERATION OF THE EXCESS CARRIERS

One of the main problems in measuring the lifetime is how to distinguish the bulk and surface contributions to the total recombination process. The lifetime measured by any method is not only affected by bulk but also by surface recombination processes. Various methods have been suggested, such as immersing, the sample in the HF solution, or measuring the fundamental lifetime on wafers which are identical except for the thickness. A microwave lifetime measurement method has been used at a frequency of 2.8 GHz in which the reflected microwave power is proportional to the average excess concentration over the whole thickness of the sample. The advantage of the harmonic generation method and analysis of the amplitude and phase of the reflected microwaves, is that it not only is highly accurate, but also gives the bulk lifetime and the surface recombination velocities at the front and back surfaces separately.