In this study, positive Hall coefficient in phosphorusdoped Zn,MgO epitaxial films grown on the undo

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• Motivation for understanding doping in ZnO
• Wide bandgap semiconductor
• Band Gap 3.4eV (direct)
• Large exciton binding energy
• Intrinsic defects yield n-type p-type difficult
  to realize
• Single crystal substrates
• Violet to UV photonics (3.0-3.9 eV)
• (Cd,Zn)O- (Mg,Zn)O
• Transparent transistors

• In this study, positive Hall coefficient in
  phosphorus-doped (Zn,Mg)O epitaxial films grown
  on the undoped ZnO buffer layers is reported. In
  particular, at low oxygen growth pressures,
  phosphorus-doped (Zn,Mg)O films are n-type, but
  are p-type when grown at higher oxygen growth
  pressure.
• The motivation for examining phosphorus doping in
  Mg-doped ZnO is two-fold. First, p-type (Zn,Mg)O
  will be necessary for LED heterostructures in
  which carrier confinement for efficient
  electron-hole recombination is needed. Second,
  the addition of Mg shifts the conduction band
  edge to higher energy, perhaps increasing the
  activation energy of the defect donor states.
• p-type conductivity observed in Hall measurements
  for (Zn0.9Mg0.1)O 2 at. P epitaxial films grown
  by pulsed-laser deposition, with Hall mobility
  5-10 cm2/V-s, carrier density 3x1016/cm3

Figure 1 Effect of oxygen partial pressure on
carrier mobility of P-doped (Zn0.9Mg0.1)O films.
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Education This work involves the collaboration
of three graduate students (Jean-Marie Erie,
Yuanjie Li, and Hyun Sik Kim) and undergraduates
(Fernando Lugo and Anwar Cumberbatch)).
The Norton group has monthly
presentations by students that include topical
reviews. The undergraduates are fully integrated
into the group, having independent research
projects in thin films and nanomaterials
Outreach This past year, the Norton group hosted
a local high school student who sought to
understand the effects ion beam irradiation on
the properties of superconducting oxides as part
a science fair project. The student is shown
below using the pulsed-laser deposition in Dr.
Nortons lab to grow thin films of YBa2Cu3O7, a
high-temperature superconducting oxide material