Study unveils a route to high hole mobility in gallium nitride

phys.org | 7/8/2019 | Staff
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Crystal-field engineering of band structure and mobility in GaN. (a),(b) Change in the GW quasiparticle band structure of GaN upon biaxial dilation and compression, respectively. The energy levels have been aligned to the conduction band minimum (CBM) and valence band maximum (VBM). (c) Electron wave function at the VBM at Γ for the undistorted wurtzite GaN structure, as well as for 2% biaxial dilation and 2% biaxial compression, respectively. (d) Crystal-field splitting Δcf versus strain and (e) corresponding hole Hall mobility at 300 K. (f) Predicted temperature-dependent hole mobility in wurtzite GaN as a function of biaxial strain. Credit: Poncé, Jena & Giustino.

Gallium nitride (GaN) is a material often used to build semiconductor power devices and light emitting diodes (LEDs). In the past, researchers have explored the possibility of realizing GaN p-channel transistors, which could aid the development of better performing computers.

Type - Transistor - Reason - Hole - Mobility

Fabricating this type of transistor, however, has so far proved to be very challenging. A key reason for this is the low hole mobility of GaN, which essentially means that "holes" (i.e., missing electrons in the material) move too slowly through the semiconductor when an electric field is applied to it.

Researchers at Oxford University and Cornell University have recently carried out a study investigating the intrinsic phonon-limited mobility of electrons and holes in wurtzite GaN. Their observations, outlined in a paper published in Physical Review Letters, suggest that the hole mobility of GaN can be increased by reversing the sign of the crystal-field splitting, lifting the split-off hole states above light and heavy holes.

Tools - Mobility - Materials - Equations - Quantum

"We were working on developing computational tools for predicting the mobility of semiconducting materials starting from the fundamental equations of quantum mechanics and using high-performance computers," Feliciano Giustino, one of the researchers who carried out the study, told Phys.org.

In physics, the mobility of charge carriers (e.g....
(Excerpt) Read more at: phys.org
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