free carrier induced substrate heating of the epitaxially grown gamnas

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Free carrier induced substrate heating of the epitaxially grown GaMnAs. Institute of Physics AS CR, Prague. Vit Novak, Kamil Olejnik, Miroslav Cukr. GaMnAs. Problem: limited Mn solubility. 7%Mn, 50 nm. 7%Mn, 50 nm. growth at T=230 C. growth at T=220 C. Measuring the (low) temperature. - PowerPoint PPT Presentation

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  • Free carrier induced substrate heating of the epitaxially grown GaMnAsInstitute of Physics AS CR, PragueVit Novak, Kamil Olejnik, Miroslav Cukr

  • GaMnAs Problem: limited Mn solubilitygrowth at T=220Cgrowth at T=230C7%Mn, 50 nm7%Mn, 50 nm

  • Measuring the (low) temperature thermocouple xpoor coupling optical pyrometry xweak radiation xsubstrate transparent

    Band-gap spectroscopy Shanabrook et al. (1992), Johnson et al. (1993),Thompson et al. (1997)commercially by kSA (BandiT)

  • Band-gap spectroscopyspectrometersubstrate heaterGaAs160C sufficient!

  • Growth minimum change in Ts measured by Tc constant heater power

  • Growth minimum change in Ts measured by Tc large change in Ts measured by BES !constant heater power

  • Absorption spectrum substrate+ GaMnAs band-gap region

  • Absorption spectrum really change of Ts ! substrate+ 40C+ GaMnAs band-gap region

  • Absorption spectrum really change of Ts ! substrate+ 40C+ GaMnAs band-gap regionNIR phononsfree carriers substrate+ GaMnAs

  • Model I.naively:solution:But ! obscured parameters inconsistencies with experiment

  • Radiation heat exchange12Qin-2Qout-2Qout-1

  • Radiation heat exchange12Qin-2Qout-2Qout-1

  • Radiation heat exchangephononsinterband substrate/epilayer absorptance as(l)absorptance

  • Radiation heat exchangephononsinterbandfree holesabsorptance substrate/epilayer absorptance as(l)

  • Radiation heat exchangephononsinterbandfree holesabsorptance substrate/epilayer absorptance as(l)

  • Radiation heat exchangephononsinterbandfree holesabsorptance substrate/epilayer absorptance as(l)

  • Radiation heat exchangephononsinterband radiation sourcesfree holes~250Cabsorptance, radiance

  • Radiation heat exchangephononsinterband~900C radiation sourcesfree holesabsorptanceabsorptance, radiance~250C

  • Radiation heat exchangephononsinterband radiation sourcesfree holesbackgroundabsorptance, radiance~250C~900C

  • Radiation heat exchangephononsinterband substrate radiationfree holesbackgroundsubstrateabsorptance, radiance~250C~900C

  • Model II.better:heater ( 200C )cells ( ~ 900C )background ( > 77K, < 200C )i :as(l, t) :t af

  • Resultsbefore growth:long after growth:

  • Resultsbefore growth:long after growth:time evolution:Th = 320CTc = 950CTb = 40C

  • Implications for DT reduction TBES-locked substrate heater power (problem: heat capacity of heater)

  • Implications for DT reduction TBES-locked substrate heater power (problem: heat capacity of heater) sample holder (or sample!) with initially strong IR absorption

  • Implications for DT reduction TBES-locked substrate heater power (problem: heat capacity of heater) sample holder (or sample!) with initially strong IR absorption

  • Implications for DT reduction TBES-locked substrate heater power (problem: heat capacity of heater) sample holder (or sample!) with initially strong IR absorption

  • Implications for DT reduction TBES-locked substrate heater power (problem: heat capacity of heater)on Mo-blockw/ sublayer sample holder (or sample!) with initially strong IR absorption

  • Bonus: record Curie temperaturealso: Nottingham groupThank you !

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