Patent ID: 11862707
Assignee: STMICROELECTRONICS S.R.L.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A normally off heterostructure field-effect transistor (HEMT), comprising:
a semiconductor heterostructure including:
a first semiconductor layer formed by gallium nitride; and
a second semiconductor layer formed by aluminum gallium nitride;

a passivation layer of dielectric material on the semiconductor heterostructure;
a trench in the passivation layer and the semiconductor heterostructure, the trench including:
a bottom surface;
a planar vertical sidewall in the semiconductor heterostructure on a first side of the trench; and
a plurality of first steps each including a respective horizontal surface higher in the trench than the bottom surface and a respective vertical surface laterally opposite the planar vertical sidewall on a second side of the trench in the semiconductor heterostructure, wherein the planar vertical sidewall extends entirely through the second semiconductor layer.