TUNNEL DEVICES ARE NOT YET MANUFACTURABLE

In spite of many remarkable prototype device performances reported usi ng semiconductor multilayers that incorporate thin tunnel barriers, it has never been established that the devices are capable of routine ma nufacture. With reference to the simplest possible tunnel device struc ture, a single similar to 3 nm thick AlAs barrier within an asymmetric doping environment in GaAs (the so-called ASPAT microwave detector di ode), we show here that is not yet possible to design, grow or qualify the semiconductor multilayers with sufficient accuracy, precision, un iformity or reproducibility that would allow reverse engineering, a pr erequisite for manufacture, to be undertaken with confidence. We descr ibe the improvements in design, growth and qualification that will be required to achieve manufacturability, and comment on the feasibility of attaining this goal. Our conclusions for thin tunnel barrier device concepts apply a fortiori to any device ideas that seek to exploit me soscopic phenomena in semiconductors.