Group III nitride based FETs and HEMTs with reduced trapping and method for producing the same
AssigneesCree Lighting Company, The Regents of the University of California
InventorsYifeng Wu, Naiqing Zhang, Jian Xu, Lee Mc Carthy
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Abstract
New Group III nitride based field effect transistors and high electron mobility transistors are disclosed that provide enhanced high frequency response characteristics. The preferred transistors are made from GaN/AlGaN and have a dielectric layer on the surface of their conductive channels. The dielectric layer has a high percentage of donor electrons that neutralize traps in the conductive channel such that the traps cannot slow the high frequency response of the transistors. A new method of manufacturing the transistors is also disclosed, with the new method using sputtering to deposit the dielectric layer.
Claims41
A field effect transistor (FET), comprising:
- a high resistivity, non-conducting layer;
- a barrier layer on said non-conducting layer;
- respective source, drain and gate contacts contacting said barrier layer, with part of the surface of said barrier layer uncovered by said contacts;
- and
- an electron source layer formed on the surface of said barrier layer between said contacts, said electron source layer having a high percentage of donor electrons, said donor electrons allowing said transistor to produce efficient gain at microwave frequencies.
A high electron mobility transistor (HEMT), comprising:
- a high resistivity, non-conducting semiconductor layer;
- a barrier layer on said high resistivity layer, said barrier layer having a wider bandgap than said high resistivity layer;
- a two dimensional electron gas between said barrier layer and said high resistivity layer;
- respective source, drain and gate contacts contacting said barrier layer, with part of the surface of said barrier layer uncovered by said contacts;
- and
- an electron source layer formed on the surface of said conductive channel between said contacts, said layer having a high percentage of donor electrons, said barrier layer having positively charged traps, said donor electrons neutralizing said traps to allow said HEMT to produce efficient gain at microwave frequencies.
A method for manufacturing a transistor with an electron source layer on its surface, comprising:
- placing said transistor in a sputtering chamber,;
- sputtering said electron source layer on said transistor in said sputtering chamber, said electron source layer providing a source of electrons to eliminate trapping and allow said transistor to provide efficient gain with AC signals applied to said gate contact;
- cooling and venting said sputtering chamber;
- and
- removing said transistor from said sputtering chamber.
A method for manufacturing a transistor with an electron source layer on its surface, comprising:
- forming said transistor and cleaning said transistor prior to placing said transistor in said sputtering chamber, wherein said transistor is cleaned by rinsing said transistor with NH4OH:H2O (1:4) for approximately 10 to 60 seconds
- placing said transistor in a sputtering chamber;
- sputtering said electron source layer on said transistor in said sputtering chamber;
- cooling and venting said sputtering chamber;
- and
- removing said transistor from said sputtering chamber.
Dependencies are inferred from the claim text.