A polarization-induced 2D hole gas in undoped gallium nitride quantum wells

Chaudhuri, Reet; Bader, Samuel James; Chen, Zhen; Muller, David A.; Xing, Huili Grace; Jena, Debdeep

doi:10.1126/science.aau8623

Cited by 129 publications

(100 citation statements)

References 49 publications

(80 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(The hole population is enhanced at negative kx, which, given the negative group velocity for holes, implies a rightward current.) (c) Model mobility versus Hall measurements reported by Chaudhuri et al7 Dashed durves are also shown for the various scattering mechanisms alone (polar optical, acoustic, and extrinsic). Note: the model is obtained by a full solution incorporating all mechanisms simultaneously, not by a Matthiessen approximation of the component limitations.…”

mentioning

confidence: 83%

Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Bader

Chaudhuri

Schubert

et al. 2019

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

To make complementary GaN electronics more than a pipe dream, it is essential to understand the low mobility of 2D hole gases in III-Nitride heterostructures. This work derives both the acoustic and optical phonon spectra present in one of the most prominent p-channel heterostructures (the all-binary GaN/AlN stack) and computes the interactions of these spectra with the 2D hole gas, capturing the temperature dependence of its intrinsic mobility. Finally, the effects of strain on the electronic structure of the confined 2D hole gas are examined and a means is proposed to engineer the strain to improve the 2D hole mobility for enhanced p-channel device performance, with the goal of enabling wide-bandgap CMOS.Decades after the celebrated invention of Mg p-doping 1 in Gallium Nitride (GaN) and the subsequent development of GaN-based LEDs, the manipulation of holes in GaN remains a fundamental challenge. Consequently, despite the expected dominance of GaN High Electron Mobility Transistors (HEMTs) in the coming generation of power electronics 2 and communications systems 3 , there is no complementary p-channel device which can be readily integrated. This incompleteness restricts the possible circuit topologies and system designs acheivable in GaN electronics, but arises quite straightforwardly from the physics of the GaN valence band. These bands, both heavy and deep in energy, have proven difficult to contact with typical metal workfunctions 4 , difficult to dope with high efficiency 5 , and difficult to flow current through with high conductivity. Nonetheless, the commercial interest in generating complementary GaNbased circuits 6 and scientific interest in studying highlydegenerate hole physics 7 have prompted great recent progress in p-channel devices 8 .Of the varied structures 6,9-16 which have been proposed as a platform for p-channel III-Nitride electronics, the single GaN/AlN heterojunction field-effect transistor has received recent attention for its high sheet conductance 7 and excellent device performance 8 . In this structure, depicted in Fig 1(a), the all-binary materials provide a straightforwardly repeatable growth with no possible parasitic electron channels, a tremendous holeinducing polarization-charge for low sheet-resistance, and maximal bandgaps for extreme voltage-handling capability. Given the recent reports of temperature-dependent transport studies in this heterostructure 7 , and recent first-principles suggestions of possible enhancements to hole mobility in bulk p-GaN 17 , this work presents a model to explain the measured mobility of the 2D hole a) sjb353@cornell.edu; http://sambader.net 2.5 0.0 2.5 ← k y [1/nm] k x → (b) HH LH 0 2 4 DOS [eV −1 nm −2 ] 150 100 50 0 50 Energy [meV] HH LH (c) 0 5 10 15 20 Depth [nm] E C E V E F p GaN 13nm AlN ↓ 2DHG 0.5 1.0 1.5 2.0 2.5 Effective mass [m e ] HH LH (d) (a) 0 1 f(k x ) f(k y ) FIG. 1. (a) A 13nm GaN layer on top of a thick AlN buffer induces a two-dimensional hole gas of density ∼ 4.4×10 13 /cm 2 , which is confined at the interface by strong p...

show abstract

mentioning

confidence: 83%

Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Bader

Chaudhuri

Schubert

et al. 2019

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is analogous to the 2DEG in an Al(Ga)N/GaN heterostructure. In a previous work, we reported the observation of this undoped GaN/AlN 2DHG with one of the highest hole densities seen across all material systems and sheet resistances ranging from ∼6–10 kΩ sq −1 , a 3× improvement in room‐temperature conductivity over previous doped 2DHGs . We next analyze the effect of the growth conditions on the resultant 2DHG channel, identify the optimum condition, and show that large‐area 2DHG wafers can be obtained.…”

Section: Resultsmentioning

confidence: 85%

“…The lowest 2DHG sheet resistances measured were ≈6 kΩ sq −1 at 300 K and ≈2 kΩ sq −1 at 77 K. These are some of the highest conductivity hole channels reported so far in III‐nitrides. We previously reported the temperature‐dependent transport of similar 2DHGs, showing that their conductivity increases as the temperature is lowered, down to ≈1 kΩ sq −1 at 10 K. In recent reports, Poncé et al and Bader et al derived that the 300 K transport of the GaN/AlN 2DHG is dominated by acoustic phonons (AP) scattering. At the low temperatures of 77 K, phonons freeze out and extrinsic scattering mechanisms such as due to interface roughness (IR) dominate.…”

Section: Resultsmentioning

confidence: 96%

“…We have recently reported the observation of the long‐missing polarization‐induced 2DHG at the undoped GaN/AlN interface—the p‐type dual of the ubiquitous undoped Al(Ga)N/GaN 2DEG, which has three times a higher conductivity than the previous reported 2DHGs. These high‐density holes give us experimental access to the largely unknown transport physics in the valence band of GaN.…”

Section: Introductionmentioning

confidence: 84%

“…Technologically, it is a promising platform to enable high‐performance p‐channel transistors toward realizing wide‐bandgap complementary circuits. In the previous report, we had demonstrated the growth of these GaN/AlN structures on small pieces less than 1 cm 2 in size. Moving these growths to larger‐area wafers will accelerate research and process development efforts, similar to how the wafer‐scale uniform growth of the AlGaN/GaN 2DEGs was a step toward enabling a production‐suitable process for HEMTs .…”

Section: Introductionmentioning

confidence: 88%

See 2 more Smart Citations

Molecular Beam Epitaxy Growth of Large‐Area GaN/AlN 2D Hole Gas Heterostructures

Chaudhuri

Bader

Chen

et al. 2020

Physica Status Solidi (b)

Self Cite

View full text Add to dashboard Cite

Large‐area growth of polarization‐induced 2D hole gases (2DHGs) in a GaN/AlN heterostructure using molecular beam epitaxy (MBE) is demonstrated. A study of the effect of metal fluxes and substrate temperature during growth is conducted to optimize the 2DHG transport. These conditions are adopted for the growth on 2 in. wafer substrates. The obtained results represent a step forward towards achieving a GaN/AlN 2DHG platform for high‐performance wide‐bandgap p‐channel field effect transistors (FETs).

show abstract

Atomic‐Scale Characterization of Negative Differential Resistance in Ferroelectric Bi₂WO₆

Song

Mao

Yang

et al. 2021

Adv Funct Materials

View full text Add to dashboard Cite

Negative differential resistance (NDR), a quantum nonlinear electron transport process, has long attracted research interest owing to its intriguing underlying physics and promising applications in high-speed electronics. Here, the authors report the NDR behavior in (001)-oriented ferroelectric Bi 2 WO 6 using scanning tunneling microscopy (STM). The current-voltage characteristics of the diode configuration consisting of an STM tip over the [BiO] + -[WO 4 ] 2− -[BiO] + terrace exhibit NDR features. Scanning tunneling spectroscopy combined with density functional theory calculations indicates that the observed NDR results from robust resonant tunneling through confined energy levels within the 2D [WO 4 ] 2− layer. The atomically resolved NDR found in such a transition metal oxide offers a unique band structure for novel ferroelectric-based devices.

show abstract

A polarization-induced 2D hole gas in undoped gallium nitride quantum wells

Cited by 129 publications

References 49 publications

Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Molecular Beam Epitaxy Growth of Large‐Area GaN/AlN 2D Hole Gas Heterostructures

Atomic‐Scale Characterization of Negative Differential Resistance in Ferroelectric Bi₂WO₆

Contact Info

Product

Resources

About

A polarization-induced 2D hole gas in undoped gallium nitride quantum wells

Cited by 129 publications

References 49 publications

Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

Molecular Beam Epitaxy Growth of Large‐Area GaN/AlN 2D Hole Gas Heterostructures

Atomic‐Scale Characterization of Negative Differential Resistance in Ferroelectric Bi2WO6

Contact Info

Product

Resources

About

Atomic‐Scale Characterization of Negative Differential Resistance in Ferroelectric Bi₂WO₆