How Successfully Does Angle-resolved Photoemission Determine the Band Structure of Semiconductors?

Both the calculation and the experimental determination of the band structure of simple materials using the techniques of photoemission have now reached levels of considerable sophistication and maturity. Indeed, it is often claimed that the determination of the detailed electronic band structure of semiconductors, for example, is almost routine using angle-resolved photoelectron spectroscopy in conjunction with synchrotron radiation. In this paper we will discuss the extent to which this claim is justified, illustrating the discussion with recent results from a number of III/V semiconductors. We will demonstrate the model-dependent nature of current interpretations of the experimental data, and will show that the technique is presently limited due to the scarcity of information concerning excited band states well above the vacuum level.