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Time-dependent hydrogen annealing of Mg-doped GaN

This study investigates the interaction between hydrogen and p-type GaN and its alloys, focusing on the effects of time-dependent annealing. The results suggest that alloying GaN with aluminum alters the kinetics of hydrogen passivation.

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Time-dependent hydrogen annealing of Mg-doped GaN

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  1. Time-dependent hydrogen annealing of Mg-doped GaN Ustun R. Sunay J. Dashdorj M. E. Zvanut This work is funded the National Science Foundation, Grant No. DMR 1006163. 

  2. Outline • Motivation • What can GaN do for us? • Background • What do we need to know about Mg-doped GaN? • Explain electron paramagnetic resonance (EPR) • Experiment • What are the parameters of our experiment? • Results • EPR spectra • Summary - Alloying GaN with aluminum changes the kinematics of hydrogen passivation.

  3. Why Care About GaN? Why Care About GaN? Other list of Applications High frequency devices High electron mobility transistors- used in radar imaging, radio astronomy, etc…. http://en.wikipedia.org/wiki/File:RBG-LED.jpg

  4. Background Mg doped GaN is a p-type semiconductor Mg concentration is ~1019 cm-3 GaN density is ~1022 cm-3 Mg+ Main Point Study hydrogen interaction in p-type GaN and its alloys. http://nanoall.blogspot.com/2011/02/nanomembranes.html

  5. H2 ”rich” atmosphere H-H Surface of sample + e- H GaN Film + Mg-N This hydrogen interaction with Mg+ makes the semiconductor less effective

  6. EPR ΔE = gμB Bo Δ E=h f Bruker Analytische Messtechnik ESP300 User’s Manual EPR Primer page 2.1

  7. Experimental Details • GaN was grown on sapphire substrate using MOCVD. • Concentration of Mg ~4x1019 cm-3 • AlxGa1-xN: x ranging from 0.00-0.28 • EPR at 4 K : Microwave frequency ~ 9.4 GHz 2.5 cm AlxGa1-xN:Mg 1 μm AlN Sample AlGaN AlN Sapphire substrate

  8. FURNACE DETAILS • Isochronal annealing steps ranged from 5 min-360 min at temperatures ranging from 300oC to 750oC in forming gas(7%H2:93%N2)

  9. Mg signal increases in intensity at low temperature anneals for 0% Al

  10. At high Al %, the process of passivating has slowed down.

  11. Summary • After annealing from 300o C - 500o C the Mg signal intensity in 0% Al increases • Preliminary data suggest that at 700oC, high % Al has a slower passivation rate • The Mg signal passivates for all samples at 700o C after being annealed for ~6 h • Alloying GaN with aluminum changes the kinematics of hydrogen passivation.

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