Lifetime broadening of Wannier-Stark states under strong Zener tunneling in superlattices

Summary form only given. The electronic structure of a periodic potential under a static electric field is of high interest due to its basic importance for carrier transport in solids. For obtaining a complete picture of the spectrum over the whole field range, the fundamental process of Zener tunneling to higher bands needs to be understood. Although this effect is used since decades in devices, very little is known, e.g., about its dynamics as a function of bias field. We present here a comparative experimental and theoretical study which investigates the dynamics of Zener tunneling and shows that the widely used Zener equation needs to be extended qualitatively to describe experiment. We have investigated a shallow 76/39 /spl Aring/ GaAs/Al/sub 0.08/Ga/sub 0.92/As superlattice which has one below-barrier electron miniband only.