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Polarization-balanced design of heterostructures: Application to AlN/GaN double-barrier structures

Kristian Berland (Institutionen för mikroteknologi och nanovetenskap, Bionanosystem) ; Thorvald Andersson (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik) ; Per Hyldgaard (Institutionen för mikroteknologi och nanovetenskap, Bionanosystem)
Physical Review B (1098-0121). Vol. 84 (2011), 24,
[Artikel, refereegranskad vetenskaplig]

Inversion and depletion regions generally form at the interfaces between doped leads ( cladding layers) and the active region of polar heterostructures like AlN/GaN and other nitride compounds. The band bending in the depletion region sets up a barrier that may seriously impede perpendicular electronic transport. This may ruin the performance of devices such as quantum-cascade lasers and resonant-tunneling diodes. Here we introduce the concepts of polarization balance and polarization-balanced designs: A structure is polarization balanced when the applied bias match the voltage drop arising from spontaneous and piezeolectric fields. Devices designed to operate at this bias have polarization-balanced designs. These concepts offer a systematic approach to avoid the formation of depletion regions. As a test case, we consider the design of AlN/GaN double-barrier structures with Al((x) over tilde)Ga(1-(x) over tilde)N leads. To guide our efforts, we derive a simple relation between the intrinsic voltage drop arising from polar effects, average alloy composition of the active region, and the alloy concentration of the leads. Polarization-balanced designs secure good filling of the ground state for unbiased structures, while for biased structures with efficient emptying of the active region they remove the depletion barriers.

Nyckelord: quantum cascade laser, resonant-tunneling diodes, molecular-beam, epitaxy, mu-m, macroscopic polarization, intersubband absorption, wells, transport, gan, semiconductors

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Denna post skapades 2012-02-02. Senast ändrad 2017-10-03.
CPL Pubid: 154725


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