It is demonstrated theoretically that a stable and tunable semiconduct
or oscillator can be designed by using a novel method of chaos control
. By application of a small time-continuous delayed feedback voltage c
ontrol signal, different unstable periodic orbits embedded in the chao
tic attractor of a semiconductor can be stabilized. Thus different mod
es of self-generated periodic voltage oscillations can be selected, fo
r example by choosing an appropriate delay time. This is illustrated f
or two different oscillation mechanisms involving hot-carrier transpor
t: (i) self-generated oscillations under crossed electric and magnetic
fields in the regime of low-temperature impurity breakdown (dynamic H
all effect), and (ii) driven real-space transfer oscillations in modul
ation-doped heterostructures.