Thermoelectric properties of In-rich InGaN and InN/InGaN superlattices

Journal Article · Fri Apr 15 04:00:00 EDT 2016 · AIP Advances

DOI:https://doi.org/10.1063/1.4948446· OSTI ID:22611676

Ju, James; Haunschild, Georg; Loitsch, Bernhard; Stoib, Benedikt; Brandt, Martin S.; Stutzmann, Martin; Koblmüller, Gregor ^[1]; Sun, Bo; Koh, Yee Kan ^[2]

---

1. Walter Schottky Institut, Physik Department, TU München, 85748 Garching (Germany)
2. Department of Mechanical Engineering, National University of Singapore, 117576 (Singapore)

The thermoelectric properties of n-type InGaN alloys with high In-content and InN/InGaN thin film superlattices (SL) grown by molecular beam epitaxy are investigated. Room-temperature measurements of the thermoelectric properties reveal that an increasing Ga-content in ternary InGaN alloys (0 < x(Ga) < 0.2) yields a more than 10-fold reduction in thermal conductivity (κ) without deteriorating electrical conductivity (σ), while the Seebeck coefficient (S) increases slightly due to a widening band gap compared to binary InN. Employing InN/InGaN SLs (x(Ga) = 0.1) with different periods, we demonstrate that confinement effects strongly enhance electron mobility with values as high as ∼820 cm{sup 2}/V s at an electron density n{sub e} of ∼5×10{sup 19} cm{sup −3}, leading to an exceptionally high σ of ∼5400 (Ωcm){sup −1}. Simultaneously, in very short-period SL structures S becomes decoupled from n{sub e}, κ is further reduced below the alloy limit (κ < 9 W/m-K), and the power factor increases to 2.5×10{sup −4} W/m-K{sup 2} by more than a factor of 5 as compared to In-rich InGaN alloys. These findings demonstrate that quantum confinement in group-III nitride-based superlattices facilitates improvements of thermoelectric properties over bulk-like ternary nitride alloys.

• OSTI ID: 22611676
• Journal Information: AIP Advances, Journal Name: AIP Advances Journal Issue: 4 Vol. 6; ISSN AAIDBI; ISSN 2158-3226
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COMPARATIVE EVALUATIONS
ELECTRIC CONDUCTIVITY
ELECTRON DENSITY
ELECTRON MOBILITY
ELECTRONS
GALLIUM COMPOUNDS
INDIUM NITRIDES
MOLECULAR BEAM EPITAXY
MOLECULAR BEAMS
REDUCTION
SUPERLATTICES
TEMPERATURE MEASUREMENT
TEMPERATURE RANGE 0273-0400 K
TERNARY ALLOY SYSTEMS
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
THIN FILMS