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

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.

Automated summary

Photoluminescence excitation spectroscopy (PLE) and high-resolution x-ray diffraction (HR-XRD) were used to characterize the structural and electronic properties of high current density InGaAs/AlAs/InP resonant tunneling diode wafer structures. Through simulation and careful selection of detection wavelength, crucial information about band-offsets was obtained non-destructively. An agreement between HR-XRD data, PL, and PLE data was achieved at a specific conduction band offset percentage of 58.8%. This scheme provides important electronic and structural information without damaging the materials.