Method for testing lifetime of surface state carrier of semiconductor

A method for testing a lifetime of a surface state carrier of a semiconductor, comprising the following steps:

• 1) using a narrow pulse light source with photon energy higher than a semiconductor forbidden band width to emit a light pulse, coupling the light pulse to an interior of a near-field optical probe through light path collimation, and producing, by the near-field optical probe, a photon-generated carrier on a surface of a semiconductor material under test through excitation;
• 2) concentrating the excited photon-generated carrier on the surface of the semiconductor material, and conducting recombination continuously with a surface state as a recombination center, wherein a recombination rate is in direct proportion to a carrier concentration and a carrier lifetime;
• 3) in both carrier excitation and recombination processes in step 1) and step 2), producing a change in a lattice constant due to an electronic volume effect, producing a stress wave, and detecting a signal of the stress wave in a high-frequency broadband ultrasonic testing mode;
• and
• 4) conducting fitting calculation on the signal of the stress wave to obtain the lifetime of the surface state carrier τc.