Observation of an inverted band structure near the surface of InN

Abstract

The dispersion of the valence band within the electron accumulation layer of n-type InN(0001) has been directly measured using angle-resolved photoemission spectroscopy. Intermixing between the heavy-hole and light-hole valence bands in the intrinsic quantum well potential associated with the near-surface electron accumulation layer results in an inverted band structure, with the valence band maximum lying away from the Brillouin zone center. Such an inverted band structure has not previously been observed in an intrinsic accumulation layer.

Tuning the Surface Charge Properties of Epitaxial InN Nanowires

“…Hence, defects and impurities in these compounds are generally donor-like, leading to extremely high electron densities even in nominally undoped structures. Common to these materials is the near-universal observation of a two-dimensional electron gas (2DEG) at the grown surfaces of both thin film and nanowire structures, the origins of which have remained a subject of intense debate. ,− For these reasons, the achievement of intrinsic and p-type InN as well as precise control over their surface charge properties has remained an elusive goal. To date, uncontrolled surface charge properties represent one of the most fundamental challenges in nanowire electronics and photonics technology development.…”

Electronic structure of InN studied using soft x-ray emission, soft x-ray absorption, and quasiparticle band structure calculations

“…We note that an inverted valence band structure within the electron accumulation layer near the surface has recently been measured using ARPES. 26 This phenomena is difficult to observe with XES, since the XES sampling depth is much greater than the depth of the accumulation layer. Further work is required in order to determine k-resolved band structure of bulk InN with resonant XES, as recently attempted for GaN.…”

Potassium and ion beam induced electron accumulation in InN

“…The top of the valence band was obtained by linear extrapolation of the leading edge. Here the top of the valence band is not actually the valence band maximum (VBM), because due to interactions between the subbands and valence band near the center of BZ, InN presents an inverted band structure and VBM is located about few degrees off normal [23]. At such a small coverage, not much effect was observed on the valence band structure (not shown here).…”

“…The surface sheet densities extracted from k F are 1.9 × 10 13 cm −2 , 3.58 × 10 13 cm −2 and 7.7 × 10 13 cm −2 respectively for clean, potassium deposited, and mild energy ion bombarded InN surfaces. The data points can be well fitted by a parabola in narrow k F range of clean InN, although, distortion from parabolic dispersion is observed for the potassium deposited and sputtered InN surfaces due to the enhanced interaction between valence and conduction band electrons with the increase in the conduction band electron density [23]. We previously investigated the effect of the strong electron-electron interaction onto the valence and conduction dispersions for InN after N 2 + ion sputtering and annealing [2,23].…”