HEMT double hetero structure

Claim 1

A high electron mobility transistor, comprising: a source region, a channel region, a drain region, and a respective contact in electrically conductive connection with said source region or, respectively, said drain region, and a gate contact; for construction of a pseudomorphic double heterostructure, an upper boundary layer that is arranged between said channel region and said gate contact, and a lower boundary region that is arranged on a side of said channel region facing away from said gate contact; said channel region and said upper and lower boundary layers being different semiconductor materials, so that a minimum of a lower boundary of a conduction band in each of said upper and lower boundary layers is greater than a maximum of the lower boundary of the conduction band in the channel region; said upper and lower boundary layers being doped n-conductive; the channel region having a mixed crystal composition that varies, continuously or in at least one step, in a direction from said lower boundary layer to said upper boundary layer, such that in the channel region at each distance from the lower boundary layer the lower boundary of the conduction band is not higher than if the mixed crystal composition in the region of this relevant distance from the lower boundary layer up to an arbitrary smaller distance from the lower boundary layer in the channel region were homogenous and equal to the mixed crystal composition in said smaller distance from the lower boundary layer; and in at least one distance from the lower boundary layer, the lower boundary of the conduction band being lower than if the mixed crystal composition in the region from the relevant distance from the lower boundary layer up to the boundary, facing the lower boundary layer, of the channel region were equal to the mixed crystal composition of the channel region at said boundary.