Compact noncontact excess carrier lifetime characterization apparatus

An apparatus for measurement of the excess carrier lifetime of a test wafer of semiconductor material, comprising:

• a first source of energy generating a beam to excite the excess carriers in a semiconductor material;
• a second source of energy generating a beam to measure the conductance of the semiconductor material;
• a mechanism for adjustment of the beam size of the energy from the first source of energy and for adjustment of the spacial energy profile of the beam from the first source of energy;
• a turning mirror, the turning mirror turning the energy beam from the first source of energy into a co-axial relation with the beam from the second source of energy;
• and
• a computer program to control the mechanism to control the beam size and spacial energy profile of the beam from the first source of energy at the test wafer.

An apparatus for measurement of the excess carrier lifetime of a semiconductor material to measure lifetimes from less than ten nanoseconds to greater than one microsecond, comprising:

• a laser for generating a beam of light;
• an optical electro-optic modulator in the path of the beam;
• a beam splitter for splitting the beam into a first portion and a second portion;
• a silicon detector, the second portion of the beam incident thereon, to monitor the temporal profile of the beam;
• a shutter in the path of the first portion of the beam;
• an attenuator in the path of the first portion of the beam;
• a positioner mounting the semiconductor material to expose a portion of the semiconductor material to the first portion of the beam, the positioner movable along a first direction parallel the beam and along second and third mutually perpendicular directions transverse the beam;
• a millimeter wave source generating a second beam of energy, the second beam incident upon the portion of the semiconductor material;
• a detector to detect energy of the second beam reflected from the semiconductor material back to the wave source;
• a digitizer to digitize the analog signal data detected by the detector;
• and
• a digital computer to analyze the digitized data to compute the excess carrier lifetime of the semiconductor material and control the duration of the laser beam and electro-optic modulator in response to the data from the silicon detector, the digital computer further positioning the positioner.

An apparatus for measurement of the excess carrier lifetime of a test wafer of semiconductor material, comprising:

• a first source of energy generating a beam to excite the excess carders in a semiconductor material;
• a second source of energy generating a beam to measure the conductance of the semiconductor material;
• a mechanism for adjustment of the beam size of the energy from the first source of energy and for adjustment of the spacial energy profile of the beam from the first source of energy;
• a millimeter wave lens horn focusing the energy from the second source of energy onto the test wafer, permitting the test wafer to be positioned at a distance from the second source of energy;
• and
• a computer program to control the mechanism to control the beam size and spacial energy profile of the beam from the first source of energy at the test wafer.