Patent ID: 11889768
Assignee: FERDINAND-BRAUN-INSTITUT GGMBH, LEIBNIZ-INSTITUT FÜR HÖCHSTFREQUENZTECHNIK
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A transistor structure, comprising:
a) a substrate (110, 210);
b) a piezoelectric active layer (112, 212), having a heterojunction, disposed on the substrate (110, 210);
c) a dielectric passivation layer (120, 220) disposed on the active layer (112, 212) and having a thickness of between 10 nm and 1000 nm, wherein the passivation layer (120, 220) has a recess (122, 222) that extends through the entire passivation layer (120, 220) in the direction of the active layer (112, 212), wherein the recess (122, 222) has a width between 10 nm and 500 nm on the boundary to the active layer (112, 212) and the ratio between the thickness of the passivation layer (120, 220) and the width of the recess (122, 222) at the boundary to the active layer (112, 212) is between 1.5:1 and 4:1;
d) a gate contact element (140, 240) disposed within the recess (122, 222), wherein the contact element (140, 240) extends from the active layer (112, 212) to above the passivation layer (120, 220); and
e) a cover layer (150, 250) that covers the contact element (140, 240) above the passivation layer (120, 220); characterized in that
f) at least one layer (120, 220, 150, 250, 230) disposed above the active layer (112, 212) is tensile stressed or compressively stressed in the area around the contact element (140, 240) with a normal tension of |σ|>1 GPa, or the cover layer is tensile stressed in the area around the contact element (140, 240) with a normal stress of σ>200 MPa,
g) wherein via the individual stresses in the area around the contact element (140, 240), a resulting force on the boundary area between the passivation layer (120, 220) and the active layer (112, 212) is set, which influences via the piezoelectric effect the electron density in the active layer (112, 212) in the area below the contact element (140, 240), wherein the normal tensions of stressed layers lie in the range between ±4 GPa.