Time response measurement of pulsed electron beam from InGaN photocathode

Abstract

The photocurrent from a semiconductor photocathode with a negative-electron affinity surface can be arbitrarily controlled by the excitation laser power. Applying this characteristic to a scanning electron microscope allows the probe current to be arbitrarily controlled at any location on the sample. A photocathode with a fast time response is required to control the probe current at high speed. This study used an InGaN photocathode for pulsed electron beam generation and investigated its time response. A pulsed electron beam with 3.8 ns pulse width and 8.1 × 103 A cm−2 current density was observed, and the rise and fall times of the photocurrent were found to be 1.7 and 2.0 ns, respectively. The results show that despite the bottleneck of the time response of the laser power, the InGaN photocathode generates an electron beam that can control the probe current on a pixel-by-pixel for a 270 MHz scan speed.

Review of photocathodes for electron beam sources in particle accelerators

“…These dopants, such as indium (In) or phosphorous (P) can decrease the E gap to a more suitable wavelength in the visible spectral range and recently published studies reported on the potential usage of such novel InGaN photocathodes. [157][158][159] 5.4.2 Preparation. The commercially available semiconductor undergoes a wet-chemical cleaning before being installed in a UHV chamber.…”

“…These dopants, such as indium (In) or phosphorous (P) can decrease the E gap to a more suitable wavelength in the visible spectral range and recently published studies reported on the potential usage of such novel InGaN photocathodes. 157–159…”

Photoelectron beam from semiconductor photocathodes leading to new inspection technologies

“…Furthermore, we focused on GaN-based semiconductors, which are wide bandgap semiconductors with the advantage of larger surface band bending (φBB) than that of a GaAs semiconductor and achieved 20 times longer lifetime [9]. Further developed InGaN semiconductor photocathodes using GaN-based semiconductor materials have achieved electron emission with energy dispersion below 0.1 eV, current density exceeding 1 kA/cm 2 , and generation of pulsed electron beams with a rise time of 1.5 ns consistent with the temporal structure of the irradiated pulsed laser [10], [11].…”

Local voltage contrast changes in MOSFET using scanning electron microscopy with photoelectron beam technology

“…2), the probe current can be selectively changed within one field of view of the SEM image. [1][2][3] This technology is called Digital Selective e-Beaming (DSeB). DSeB is implemented by synchronizing the laser output signal that irradiates the photocathode with the SEM scan signal (Fig.…”