Observation of p-n Junctions with a Flying-Spot Scanner Using a Chopped Photon Beam

Abstract

A flying-spot scanner that employs a chopped photon beam emitted from a cathode ray tube is reported. The photon beam scanns a planar p-n junction put on a metal electrode through a In2O3-coated transparent electrode and a 15 µm-thick mylar spacer. The ac photovoltage is picked up with electrodes through a condensor formed by the spacer. The photovoltage signal modulates brightness of another cathode ray tube to form a scanning image. Mean wavelength and chopping frequency of the photon beam are 507 nm and 2 kHz. Scanning image analysis is done using photocurrent density equations based on a step-like junction model. Three kinds of junctions, a solar cell, a partly-deep junction and a non-uniformly ion implanted one, have been evaluated to show the validity of the present method.

Surface photovoltage phenomena: theory, experiment, and applications

“…Subsequently, his approach has been used by many other scientists. An insulating spacer (e.g., mylar) may replace the air/vacuum gap (see, e.g., [213]), as long as the placement of the spacer does not alter the surface properties of the semiconductor.…”

“…On the other hand, as noted in Section 2.2.2, 3 must not be too high or the ac SPV will differ appreciably from the dc SPV. Thus, the measurement is precise if and only 3 is inside a limited range [213]. The minimal 3 necessary may be lowered if R i and/or C ins are increased.…”

“…The minimal 3 necessary may be lowered if R i and/or C ins are increased. However, increasing the former may increase the noise and also lengthen the time-constant of the lock-in ampli®er [213]. An increase of C ins may be achieved by decreasing the sample-to-metal distance.…”

Water‐based sonochemical cleaning in the manufacturing of high‐efficiency photovoltaic silicon wafers

“…Then the pressure and displacement peak amplitudes are found to be ≈ 3.5 MPa and 13 μm at U 0 = 225 V. SPV transients are measured in the capacitor rrangement [5], and details of our setup are given elsewhere [6]. The scanning SPV apparatus based on the the AC-SPV technique [7] and utilizing a "flying spot" arrangement [8] is used for obtaining SPV decays and spatially-resolved SPV maps. This technique is capable of providing wafer maps of both the photovoltage magnitude and carrier lifetime with a 100-μm spatial resolution.…”

AC Photovoltaic Detection of Buried Structures of Semiconductor Wafers

“…AC photovoltage (PY) and surface photovoltage (SPV) measurements, as nondestructive methods, have been used successfully to monitor the change of electronic properties induced by the latent scratches, polishing and other processing in semiconductor materials and devices [1][2][3].…”