Resonant Tunneling in Double Superlattice Barrier Heterostructures

We have invest igated resonant tunnel ing in double barr ier heterostructures in which the tunnel barr iers have been replaced by short period superlattices, and have shown for the first t ime quantum well confinement in a s ingle quantum well bounded by superlattices. These results also demonstrate the first u t i l iza t ion of shor t period b ina ry super la t t ices as effective t unne l barr iers to replace the conventional AlxGal_xAs barriers. The superlatt ice structure does not exhibit the asymmetry around zero bias in the electrical characterist ics normal ly observed in the conventional AlxGal .xAs bar r i e r structures, suggestive of reduced roughness at the inver ted interface by s u p e r l a t t i c e smoo th ing . The s u p e r l a t t i c e b a r r i e r a lso e x h i b i t s an anomalous ly low b a r r i e r he ight . The per formance of th i s symmet r i c supe r l a t t i c e s t ruc tu re is compared wi th an i n t e n t i o n a l l y cons t ruc ted asymmetric double barr ier superlat t ice structure, which exhibits pronounced asymmetry in the electrical characteristics. The observed behavior supports the view tha t resonant enhancement occurs in the quantum well.