Mapping of the electrostatic potentials in MOCVD and hybrid GaN tunnel junctions for InGaN/GaN blue emitting light emitting diodes by off-axis electron holography correlated with structural, chemical, and optoelectronic characterization

Off-axis electron holography has been used to measure the width of depletion region in a series tunnel junction GaN light emitting diodes that have prepared using different growth processes for blue emission. The total measured potentials are combinations mean inner potential, dopant and piezoelectric contributions. potential unmixed from such junctions can be measured. experimental results then compared secondary ion mass spectrometry, simulations, opto-electronic testing. We find widths consistent with simulations as well current density voltage characteristics. As such, off-axis demonstrated unique technique reproducibly electrostatic nm-scale resolution real III–V device specimens.