p‐Type Doped AlAsSb/GaSb Resonant Tunneling Diode Photodetector for the Mid‐Infrared Spectral Region

Abstract

In a recent publication, we proposed to apply the resonant tunneling diode (RTD) photodetector principle to the mid-infrared (MIR) spectral region, by combining an antimony-based AlSb/ GaSb double barrier quantum well (DBQW) resonant tunneling structure (RTS) with an narrow bandgap absorption region. [17] Hereby, the RTD serves as an internal high-gain amplifier of small optically generated electrical signals. In contrast to, e.g., avalanche photodiodes where the gain is provided via impact ionization processes, the gain of RTD photodetectors originates from the modulation of a larger majority charge carrier tunneling current that is sensitive to small variations of the local electrostatic potential.The so called 6.1 Å family, [18] which is comprised of the three semiconductors InAs, GaSb, and AlSb offers a huge flexibility in designing electronic, optical, and optoelectronic devices, [19] such as topological insulators, [20][21][22][23] optical MIR type-II superlattice photodetectors, [24] and quantum cascade lasers (QCLs), [25][26][27] or interband cascade lasers (ICLs), [27][28][29][30][31] and interband cascade detectors (ICDs). [32,33] This flexibility can mainly be attributed to the huge variety of band lineups, bandgap energies, and in particular to the so called InAs/GaSb type-II broken bandgap alignment. While the InAs/GaSb/AlSb material system has also brought forth a large variety of different resonant tunneling structures, [3,18,34,35] only AlAsSb/GaSb RTDs provide the required energy barriers in both valence and conduction band due to the type-I heterointerface. [36][37][38][39] In another recent publication, we demonstrated that room temperature resonant tunneling of electrons in AlAsSb/GaSb RTDs requires the use of emitter prewells. [40][41][42] Here, we propose to invert the charge carrier polarity within the RTD photodetector, i.e., using p-type instead of n-type doping.Using p-type doping in an RTD photodetector, and therefore hole instead of electron transport, might seem counterintuitive at first, since hole transport usually comes with several disadvantages. Due to their higher effective mass, holes have a lower mobility and a smaller de Broglie wavelength compared to electrons. [43] A lower mobility results in inferior transport properties, a smaller de Broglie wavelength demands a higher quality semiconductor crystal growth. However, and in particular for the GaSb material system, p-type doping may Mid-infrared (MIR) resonant tunneling diode (RTD) photodetectors based on a p-type doped AlAsSb/GaSb double-barrier quantum well (DBQW) are proposed and investigated for their optoelectronic transport properties. At room temperature, a distinct resonant tunneling current with a region of negative differential conductance is measured. The peak-to-valley current ratio (PVCR) is 1.51. To provide photosensitivity within the MIR spectral region, a lattice-matched quaternary low-bandgap GaInAsSb absorption layer with cutoff wavelength of λ = 2.77 μm is integrated near the DBQW. Under illumination with ...

Peculiarities in optical response of hybrid-barrier GaSb/InAs/AlSb resonant tunneling diode structure

“…Figure 2a presents the evolution of PR spectra with the sample's temperature. At low energy side we observed the e1h1 transition, followed by a transition we marked GaInAsSb-i, and further the signal originating from the GaInAsSb bulk absorption layer (agreeing with the expected low temperature band gap for this quaternary compound [14,19]). The asymmetry in the widths of the QWs building up the DBS leads to the formation of a second bound electron state e2 which is confined mainly on the side of the 1.5 nm thick InAs quantum well (see Fig.…”

“…1a) is deposited which serves as a main absorption medium of a RTD-based photodetector to get its sensitivity in the MIR [18]. The composition of the quaternary absorption layer is adjusted to be lattice-matched to the GaSb substrate and its room temperature band gap is about 0.45 eV [14]. The top contact layer is made of 295 nm thick 3 × 10 18 cm -3 p-doped GaSb.…”

“…As an emerging solution there have been demonstrated resonant tunneling diode photodetectors (RTD-PDs) [12] as a fabrication and cost-effective alternative to cascaded detectors. GaSb-based RTD-PDs exhibit spectral response in the MIR [13][14][15], possess much simpler layer structure and, due to its intrinsic properties, enable high current multiplication factors [16]. Thus, RTD-PD together, for instance with GaSb-based ICLs or superluminescent diodes [17], are promising candidates for realization of an on-chip low-cost gas spectrometer.…”

Resonant Tunneling Diode Photonics

“…Several groups world-wide have worked on RTD or more generally tunneling devices as integrated amplifiers in photodetectors. Although in this chapter we concentrated on the review of RTD-PD operating in near infrared for optical communication systems and radio-over-fiber wireless communication systems, but the concept has general applicability and has been used for mid-infrared detectors [91,113] and large amplification factors have been reported -up to 10 5 excess electrons for one absorbed photon [91].…”

Determination of carrier density and dynamics via magneto-electroluminescence spectroscopy in resonant tunneling diodes

“…Understanding the paths through which carriers travel and accumulate along the structure helps to design high quality devices. 11,12 Heterostructure engineering enables the enhancement and optimization of the RTD figures of merit, such as the peak-to-valley current ratio (PVCR) and peak current density. 13 In that sense, the insertion of an emitter prewell adjacent to the double barrier has proven to be a relevant design recipe.…”