Band engineering in Al0.5Ga0.5N∕GaN superlattice by modulating Mg dopant

The electronic structures of Mg modulation-doped and undoped Al 0.5 Ga 0.5 N ∕ Ga N superlattices (SLs) are investigated by using first-principles density function theory. The layer-projected densities of states indicate that the band alignment is changed from type I to type II and the band bending due to polarization is reduced significantly by modulating Mg dopant in AlGaN layer. It is further confirmed by the calculations of the partial charge density profiles and the valence band offsets where the valence-band maximum of AlGaN in Mg modulation-doped SL is located above that of GaN. The strong hybridization between N and Mg orbitals plays an important role on the upward shifts of the valence band edges.

[1]  J. Waldrop,et al.  Measurement of AlN/GaN (0001) heterojunction band offsets by x‐ray photoemission spectroscopy , 1996 .

[2]  Kevin F. Brennan,et al.  The Physics of Semiconductors: With Applications to Optoelectronic Devices , 1999 .

[3]  W. Mitchel,et al.  Theory of the composition dependence of the band offset and sheet carrier density in the GaN/AlxGa1−xN heterostructure , 2004 .

[4]  J. W. Graff,et al.  Improved mobilities and resistivities in modulation-doped p-type AlGaN/GaN superlattices , 2001 .

[5]  Vincenzo Fiorentini,et al.  MACROSCOPIC POLARIZATION AND BAND OFFSETS AT NITRIDE HETEROJUNCTIONS , 1998 .

[6]  Lester F. Eastman,et al.  Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures , 1999 .

[7]  David H. Tomich,et al.  Optimization of InAs/GaSb type-II superlattices for high performance of photodetectors , 2004 .

[8]  Adam W. Saxler,et al.  Polarization-enhanced Mg doping of AlGaN/GaN superlattices , 1999 .

[9]  C. T. Foxon,et al.  Isoelectronic doping of AlGaN alloys with As and estimates of AlGaN/GaN band offsets , 2003 .

[10]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .

[11]  Paolo Lugli,et al.  AlN and GaN epitaxial heterojunctions on 6H–SiC(0001): Valence band offsets and polarization fields , 1999 .

[12]  Blöchl,et al.  Projector augmented-wave method. , 1994, Physical review. B, Condensed matter.

[13]  Martin Walther,et al.  High performance InAs/Ga1-xInxSb superlattice infrared photodiodes , 1997 .

[14]  F. Bernardini,et al.  First-principles prediction of structure, energetics, formation enthalpy, elastic constants, polarization, and piezoelectric constants of AlN, GaN, and InN: Comparison of local and gradient-corrected density-functional theory , 2001 .

[15]  Martin,et al.  Theoretical calculations of heterojunction discontinuities in the Si/Ge system. , 1986, Physical review. B, Condensed matter.

[16]  Wang,et al.  Correlation hole of the spin-polarized electron gas, with exact small-wave-vector and high-density scaling. , 1991, Physical review. B, Condensed matter.

[17]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[18]  K. Kumakura,et al.  Enhanced Hole Generation in Mg-Doped AlGaN/GaN Superlattices Due to Piezoelectric Field , 1999 .

[19]  Jerry R. Meyer,et al.  Type‐II quantum‐well lasers for the mid‐wavelength infrared , 1995 .