Abstract: A field effect gas sensor, for detecting a presence of a gaseous substance in a gas mixture, the field effect gas sensor comprising: a SiC semiconductor structure; an electron insulating layer covering a first portion of the SiC semiconductor structure; a first contact structure at least partly separated from the SiC semiconductor structure by the electron insulating layer; and a second contact structure conductively connected to a second portion of the SiC semiconductor structure, wherein at least one of the electron insulating layer and the first contact structure is configured to interact with the gaseous substance to change an electrical property of the SiC semiconductor structure; and wherein the second contact structure comprises: an ohmic contact layer in direct contact with the second portion of the SiC semiconductor structure; and a barrier layer formed by an electrically conducting mid-transition-metal oxide covering the ohmic contact layer.

Abstract: A field effect transistor (20) for chemical sensing, comprising an electrically conducting and chemically sensitive channel (2) extending between drain (5) and source (6) electrodes. A gate electrode (7) is separated from the channel (2) by a gap (10) through which a chemical to be sensed can reach the channel (2) which comprises a continuous monocrystalline graphene layer (2a) arranged on an electrically insulating graphene layer substrate (1). The graphene layer (2a) extends between and is electrically connected to the source electrode (5) and the drain electrode (6). The substrate supports the graphene layer, allowing it to stay 2-dimensional and continuous, and enables it to be provided on a well defined surface, and be produced and added to the transistor as a separate part. This is beneficial for reproducibility and reduces the risk of damage to the graphene layer during production and after. Low detection limits with low variability between individual transistors are also enabled.

Abstract: A field effect transistor (20) for chemical sensing, comprising an electrically conducting and chemically sensitive channel (2) extending between drain (5) and source (6) electrodes. A gate electrode (7) is separated from the channel (2) by a gap (10) through which a chemical to be sensed can reach the channel (2) which comprises a continuous monocrystalline graphene layer (2a) arranged on an electrically insulating graphene layer substrate (1). The graphene layer (2a) extends between and is electrically connected to the source electrode (5) and the drain electrode (6). The substrate supports the graphene layer, allowing it to stay 2-dimensional and continuous, and enables it to be provided on a well defined surface, and be produced and added to the transistor as a separate part. This is beneficial for reproducibility and reduces the risk of damage to the graphene layer during production and after. Low detection limits with low variability between individual transistors are also enabled.

Abstract: A field effect gas sensor (1) for detection of at least one non-hydrogen containing substance in a gas comprising hydrogen or hydrogen-containing substances. The field effect gas sensor comprises a semiconductor layer (2,3) having a surface, at least one ohmic contact (8) contacting the semiconductor (3), a first electron insulating layer (7) covering at least a part of the surface of the semiconductor layer, a second insulating layer (11) comprising a material substantially chemically inert to hydrogen or hydrogen-containing substances, the second insulating layer contacting at least one of the first electron insulating layer (7) and the semiconductor layer (3), at least one electrical contact (12) contacting the second insulating material (11) and comprising a conducting, semi-conducting and/or ion conducting layer.