Future applications of heterostructures

In this review the status and future of heterostructure devices is discussed. The author concentrates on III/V and Si/SiGe. Performance and applications are folded to the data and expectations of the micro- and opto-electronic market and to the traditional Si-mainstream. New trends, i.e. the SIA-roadmap, are checked how heterodevices can fit in. Only the most attractive candidates for applications are considered, i.e. the heterobipolar-, the hetero field effect-transistors, the resonant tunnel diode and to a less extent, some optoelectronic devices. Considered figures of merit are frequencies, transconductance, noise at high and low frequencies, threshold voltage, power delay, threshold current and quantum efficiencies. It is pointed out how to optimize those by material and design. Extrapolations to the future potential of heterodevices are made, just taking the claimed scaling of lateral dimensions into consideration. Field of applications are presented, where heterodevices offer exclusive qualities, i.e. high frequency transmission and sensors, and new mixed systems. In the case of logic the trend goes to nanoscaled devices and ICs targeting nanoelectronics beyond traditional electronics. Heterostructure layers allow a vertical nanoscaling and thus give an additional degree of freedom for designing and optimation. It is an attractive challenge for scientists and engineers to solve the related technological problems like thin, low thermal budget oxides, like defect free buffer layers etc. Special attention is put on Si/SiGe, which is now on an upswing in electronics and photonics.