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Implementation of the GaN lateral polarity junction in a MESFET utilizing polar doping selectivity
Author(s) -
Collazo Ramón,
Mita Seiji,
Xie Jinqiao,
Rice Anthony,
Tweedie James,
Dalmau Rafael,
Sitar Zlatko
Publication year - 2010
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200982629
Subject(s) - materials science , polar , mesfet , optoelectronics , ohmic contact , doping , schottky barrier , semiconductor , polarity (international relations) , transistor , field effect transistor , nanotechnology , chemistry , electrical engineering , voltage , layer (electronics) , physics , biochemistry , astronomy , diode , cell , engineering
The difference in surface energies between the Ga‐polar orientation and the N‐polar orientation of GaN translates into a completely different behavior for the incorporation of intentional and unintentional impurities. Oxygen is found to be an impurity with higher concentration in the N‐polar films than in Ga‐polar films and is the cause of n‐type conductivity observed in N‐polar films. Utilizing this doping selectivity we fabricated a depletion‐mode metal‐semiconductor field effect transistor (MESFET) with n‐type N‐polar domains as source and drain and a Ga‐polar channel on polarity‐patterned wafers. The difference in the electronic properties of the different domains, i.e., as‐grown N‐polar domains are n‐type conductive and Ga‐polar domains are insulating, allows for laterally selective doped areas that can be realized for improving contact resistance to the n‐type conduction channel. Basically, the N‐polar domains acted as the ohmic contacts to the channel localized in a Ga‐polar domain. A MESFET with a Schottky gate was fabricated as an example of implementation of this novel structure showing a lowering in the specific contact resistivity.