Wide bandgap semiconductor characterization based on capacitance characteristics acquired using corona surface charge neutralization by UV radiation pulses

A system for characterizing semiconductor doping in a wide bandgap semiconductor sample, the system comprising:

• a surface voltage measurement probe;
• a corona charge source;
• a UV radiation source;
• a moveable wafer chuck configured to support the semiconductor sample relative to the surface voltage measurement probe, the corona charge source, and the UV radiation source;
• and
• a computer controller in communication with the surface voltage measurement probe, the corona charge source, the UV radiation source, and the moveable wafer chuck, the computer controller being programmed to cause the system to:
• (i) deposit, using the corona charge source, a corona charge on a surface of the semiconductor sample in the dark to bias a region of the semiconductor sample to depletion;
• (ii) measure, using the surface voltage measurement probe, a surface voltage at the region in the dark after depositing the corona charge;
• (iii) irradiate, using the UV radiation source, the region with a series of ultraviolet (UV) radiation pulses to neutralize the deposited corona charge in a series of incremental steps, each comprising a short UV radiation wavelength, λ, a photon flux, Φ, and a pulse duration, Δtp corresponding to a linear corona charge neutralization range, wherein increments of neutralized corona charge, ΔQ, are linear with the pulse duration, Δtp;
• (iv) measure, using the surface voltage measurement probe, the surface voltage at the region in the dark before and after each UV radiation pulse and determining an average voltage in the UV radiation pulse, and an incremental change of the surface voltage, ΔV, corresponding to the UV radiation pulse;
• (v) calculate a capacitance-voltage (C-V) characteristic for the region based on a series of capacitance (C) values and surface voltage (V) values, the capacitance (C) values being determined for each UV radiation pulse based on a ratio
• Δ
• ⁢
• t
• p
• Δ
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• V
• for the corresponding UV radiation pulse and a calibration constant fcal relating a neutralized charge increment ΔQ to the pulse duration for specific UV radiation photon flux, Φ, as ΔQ=fcal·Δtp;
• and
• (vi) determine one or more electrical parameters for the semiconductor sample at the region based on the capacitance-voltage (C-V) characteristic.