Lateral III/V heterostructure field effect transistor
The invention relates to a lateral field effect transistor, in particular a HEMT having a heterostructure, in a III/V semiconductor system with a p-type semiconductor being arranged between an ohmic load contact, in particular a drain contact, and a gate contact of the transistor for an injection of holes into a portion of the transistor channel. Further, a recombination zone implemented by a floating ohmic contact is provided for to improve the device performance.
1. A lateral field effect transistor, comprising:
a III/V semiconductor heterostructure having a III/V semiconductor channel layer and a III/V semiconductor barrier layer, the III/V semiconductor barrier layer having a larger band gap than the III/V semiconductor channel layer and being adjacent to the III/V semiconductor channel layer, the III/V semiconductor heterostructure defining a lateral transistor channel near an interface between the III/V semiconductor channel layer and the III/V semiconductor barrier layer and extended in a lateral direction;
at least two ohmic load contacts for contacting the lateral transistor channel;
at least one gate contact between the at least two ohmic load contacts, in the lateral direction;
a p-type semiconductor between one of the at least two ohmic load contacts and a proximate one of the at least one gate contact, in the lateral direction, for an injection of holes into a portion of the transistor; and
an ohmic contact as a recombination zone for the injected holes, the ohmic contact being arranged between the p-type semiconductor and the proximate gate contact, in the lateral direction,
wherein the ohmic contact is floating.
2. The lateral field effect transistor of claim 1 , wherein a distance between the ohmic contact and the p-type semiconductor is in a range of 0.2 μm to 1.0 μm.
3. The lateral field effect transistor of claim 1 , wherein the group V element of the III/V semiconductor heterostructure comprises N.
4. The lateral field effect transistor of claim 3 , wherein the III/V semiconductor heterostructure is GaN-based and/or AlN-based.
5. The lateral field effect transistor of claim 1 , wherein the lateral field effect transistor is implemented as a normally-off transistor and further comprises an additional p-type semiconductor between the at least one gate contact and the lateral transistor channel.
6. The lateral field effect transistor of claim 5 , wherein the lateral field effect transistor has two gate contacts per transistor cell and is implemented as a bidirectional field effect transistor, wherein, for a given operation direction of the bidirectional field effect transistor, the additional p-type semiconductor between one of the two gate contacts and the lateral transistor channel is effective as the p-type semiconductor between one of the at least two ohmic load contacts and the proximate gate contact and the other one of the two gate contacts is effective as the gate contact between the at least two ohmic load contacts, and wherein, for the opposite operation direction of the bidirectional field effect transistor, the two gate contacts are effective in the opposite manner.
7. The lateral field effect transistor of claim 1 , wherein the ohmic contact between the p-type semiconductor and the proximate gate contact has a length, in the lateral direction, of between 0.2 μm and 1.9 μm.
8. The lateral field effect transistor of claim 1 , wherein the at least two ohmic load contacts are arranged on a side of the III/V semiconductor barrier layer opposite to a substrate.
9. The lateral field effect transistor of claim 8 , wherein the at least one gate contact is arranged in a region, in the lateral direction, where the III/V semiconductor barrier layer has a recess on the side opposite to the substrate.
10. The lateral field effect transistor of claim 1 , further comprising a further III/V semiconductor layer on a substrate side of the III/V semiconductor channel layer.
11. The lateral field effect transistor of claim 10 , wherein the further III/V semiconductor layer is extended between the at least two ohmic load contacts and is uninterrupted therebetween, in the lateral direction, wherein the at least two ohmic load contacts are on a side of the further III/V semiconductor layer opposite to a substrate, and wherein the further III/V semiconductor layer has a larger band gap than the III/V semiconductor channel layer.
12. The lateral field effect transistor of claim 11 , wherein the further III/V semiconductor layer is a back barrier layer and the ohmic contact extends through the III/V semiconductor channel layer at least to the back barrier layer.
13. The lateral field effect transistor of claim 1 , wherein the lateral field effect transistor has only one gate contact per transistor cell, wherein a distance between the gate contact and one of the at least two ohmic load contacts is larger than a distance between the gate contact and another one of the at least two ohmic load contacts, and wherein the at least two ohmic load contacts are of the respective transistor cell of the gate contact.
14. A method of manufacturing a field effect transistor, the method comprising:
producing a III/V semiconductor heterostructure having a III/V semiconductor channel layer and a III/V semiconductor barrier layer, the III/V semiconductor barrier layer having a wider band gap than the III/V semiconductor channel layer and being adjacent to the III/V semiconductor channel layer, the III/V semiconductor heterostructure defining a lateral transistor channel between the III/V semiconductor channel layer and the III/V semiconductor barrier layer and extended in a lateral direction;
producing at least two ohmic load contacts for contacting the lateral transistor channel;
producing at least one gate contact between the at least two ohmic load contacts, in the lateral direction;
producing a p-type semiconductor between one of the at least two ohmic load contacts and a proximate one of the at least one gate contact, in the lateral direction, for an injection of holes into a portion of the transistor channel; and
producing an ohmic contact as a recombination zone for the injected holes, the ohmic contact being arranged between the p-type semiconductor and the proximate gate contact, in the lateral direction,
wherein the ohmic contact is floating.
15. The method of claim 14 , wherein the ohmic contact is produced in one with and similar to the at least two ohmic load contacts.