title: Power factor enhancement by modulation doping in bulk nanocomposites.
abstract: We introduce the concept of modulation doping in three-dimensional nanostructured bulk materials to increase the thermoelectric figure of merit. Modulation-doped samples are made of two types of nanograins (a two-phase composite), where dopants are incorporated only into one type. By band engineering, charge carriers could be separated from their parent grains and moved into undoped grains, which would result in enhanced mobility of the carriers in comparison to uniform doping due to a reduction of ionized impurity scattering. The electrical conductivity of the two-phase composite can exceed that of the individual components, leading to a higher power factor. We here demonstrate the concept via experiment using composites made of doped silicon nanograins and intrinsic silicon germanium grains.
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Mona
authors.initials: M
authors.lastname: Zebarjadi
authors.forename: Giri
authors.initials: G
authors.lastname: Joshi
authors.forename: Gaohua
authors.initials: G
authors.lastname: Zhu
authors.forename: Bo
authors.initials: B
authors.lastname: Yu
authors.forename: Austin
authors.initials: A
authors.lastname: Minnich
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Lan
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Wang
authors.forename: Mildred
authors.initials: M
authors.lastname: Dresselhaus
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Ren
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
mesh_terms: D001895:Boron / Q000737:chemistry*; D004553:Electric Conductivity; D005857:Germanium / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D005857:Germanium; D001895:Boron; D012825:Silicon