Structural and electrical transport properties of MOVPE-grown pseudomorphic AlAs/InGaAs/InAs resonant tunneling diodes on InP substrates

Abstract

We report metal–organic vapor-phase epitaxy (MOVPE) growth of pseudomorphic AlAs/InGaAs/InAs resonant tunneling diodes (RTDs) on InP substrates for the first time. X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) observations reveal that a uniform strained InAs subwell is coherently grown in the double-barrier (DB) structure. The AlAs/InGaAs/InAs RTDs exhibit excellent current–voltage characteristics with a high peak current density (J P) of around 2 × 105 A/cm2 and peak-to-valley ratio (PVR) of around 6. A comparison with control RTDs consisting of AlAs/In0.8Ga0.2As DB confirms the effectiveness of InAs subwell insertion for the improvement of PVR.

Fabrication, characterisation, and epitaxial optimisation of MOVPE-grown resonant tunnelling diode THz emitters

“…Epitaxial layer perfection has been shown to be a critical criteria in the operation of these devices 6 , and for this purpose most devices are epitaxially grown using a slow-growth rate, high-vacuum MBE reactor. However, our work replicates earlier successes of high-quality growth using the commercially-scalable MOVPE 7 . We may note that this structure is completely strain-balanced due to the AlAs layers contributing with tensile stress, whereas the QW inducing compressive stress.…”

“…al. 7 , we have determined that our device is sat above the established bACK (4)kl #> e trend line. As seen in Figure 5, an ideal device was suggested to have both high peak current densities and a high peak to valley current ratio (PVCR), quantities that come as a natural trade-off as the current density is largely a function of the barrier width, which in turn affects the resonance linewidth, a quantity directly proportional to the PVCR 10 .…”

“…Figure 5. Previous assessment criteria of RTDs, with additions after Sugiyama et al 7 The peak to valley current ratio and current density on a log-log plot. Our high-J RTDs are shown with the left and right-pointing triangles (colour online)…”

Epitaxial Designs for Maximizing Efficiency in Resonant Tunneling Diode Based Terahertz Emitters

“…Qualitatively, enhancing PVCR (or Jpeak) without a reduction in Jpeak (or PVCR) (or increasing both simultaneously) has been highlighted as advantageous in increasing THz emission power [16]. We previously suggested how improvement of both leads to a marked improvement in THz emission power [22].…”

“…Experimentally, attempts to maximize the output power of RTD-based THz emitters through band-gap engineering of the epitaxial structure include: collector delta-doping or grading alloy content of the emitter [15], a sub-well [16], lowering conduction losses [8], in addition to modifications to the antenna element [17]. Such attempts often come with the risk of sacrificing epitaxial growth quality [18], requiring careful consideration of stress accumulation due to lattice misfit [19].…”