Abstract
We present an advanced nondestructive characterization scheme for high current density AlAs/InGaAs resonant tunneling diodes pseudomorphically grown on InP substrates. We show how low-temperature photoluminescence spectroscopy (LT-PL) and high-resolution X-ray diffractometry (HR-XRD) are complementary techniques to increase the confidence of the characterized structure. The lattice-matched InGaAs is characterized and found to be of high quality. We discuss the inclusion of an undoped “copy” well (C-well) in terms of enhancements to HR-XRD and LT-PL characterization and quantify the improved precision in determining the structure. As a consequence of this enhanced precision in the determination of physical structure, the AlAs barriers and quantum well (QW) system are found to contain nonideal material interfaces. Their roughness is characterized in terms of the full width to half-maximum of the split LT-PL emission peaks, revealing a ±1 atomic sheet variance to the QW width. We show how barrier asymmetry can be detected through fitting of both optical spectra and HR-XRD rocking curves.
Highlights
Resonant tunneling diodes (RTDs) are a class of unipolar, n+ doped shallow-emitter devices with active regions typically within 20–100 nm for electronic devices and typically 1 μm for optical devices
We show how low-temperature photoluminescence spectroscopy (LT-PL) and high-resolution X-ray diffractometry (HR-XRD) are complementary techniques to increase the confidence of the characterized structure
We have presented a nondestructive characterization scheme for high current density RTDs capable of describing the atomically thin AlAs barriers, via incorporation of a buried copy of the active region (C-Well)
Summary
Resonant tunneling diodes (RTDs) are a class of unipolar, n+ doped shallow-emitter devices with active regions typically within 20–100 nm for electronic devices and typically 1 μm for optical devices. We present an essential component toward improving the quality of the epitaxial interfaces, a nondestructive characterization scheme which can be used as a qualitative and quantitative measure to decrease the statistical process variability for the manufacturing of RTD material To this end, the established complementary techniques of high-resolution X-ray diffractometry (HR-XRD) and low-temperature photoluminescence spectroscopy (LT-PL) are deployed in tandem. The DBRTS is strained pseudomorphically: structure A, as seen, uses an overall tensile 4 ML symmetric AlAs barrier with a 13 ML QW, whereas structure B employs a 15 ML QW closer to the overall strain-balanced point We have discussed these advanced structural design considerations of the DBRTS in the previous work.[7] The chemically sensitive dark-field (002) TEM images correspond to FIG. We attribute this asymmetry to gettering of atomic oxygen impurities present in the reactor chamber
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