Photoluminescence excitation spectroscopy for structural and electronic characterization of resonant tunneling diodes for THz applications

Abstract

Photoluminescence excitation spectroscopy (PLE) and high-resolution x-ray diffraction (HR-XRD) are used to characterize the structural and electronic properties of high current density InGaAs/AlAs/InP resonant tunneling diode wafer structures. The non-destructive assessment of these structures is challenging, with several unknowns: well and barrier thickness, the well indium molar fraction, and band-offsets, which are a function of strain, material, growth sequence, etc. The low temperature PL spectra are deconvoluted through simulation and are shown to include contributions from type I (e1–hh1) and type II (conduction band–hh1) transitions that are broadened due to interface fluctuations on a range of length scales. PLE data are obtained by a careful choice of the detection wavelength, allowing the identification of the e2hh2 transition that is critical in determining the band-offsets. An agreement between the HR-XRD data, the PL, and the PLE data is only obtained for a given conduction band offset of 58.8%. This scheme, combining HR-XRD, PL, and PLE, consequently provides crucial electronic and structural information non-destructively.

Micro-photoluminescence characterisation of structural disorder in resonant tunneling diodes for THz applications

“…We initially demonstrated the use of PL as a rapid non-destructive characterization technique [2] to evaluate the doping profile and the QW characteristics. Further work demonstrated a non-destructive characterization scheme based on low-temperature photoluminescence spectroscopy (PL) in combination with high-resolution X-ray diffraction (HD-XRD), improved by the inclusion of a buried undoped "copy" QW [3] Additional improvement on the repeatability of the epitaxial structure has been obtained by applying photoluminescence excitation spectroscopy (PLE), used to deduce critical information on the band offset [4] Comparison with TEM underlined how critical structural parameters can be derived from this non-destructive postgrowth characterization scheme [5].…”

Micro-PL analysis of high current density resonant tunneling diodes for THz applications

“…We previously proposed a non-destructive characterization scheme based on low-temperature photoluminescence spectroscopy (PL) in combination with high-resolution X-ray diffraction (HD-XRD), improved by the inclusion of a buried undoped "copy" QW [8]. Critical information on the band offset has subsequently been obtained by applying photoluminescence excitation spectroscopy (PLE) with the additional benefit of an overall improvement in the repeatability of the realised epitaxial structure [10]. It is important to note that several important non-destructive characterisation techniques perform significant spatial-measurement averaging of a sample.…”