High electron mobility InN

Abstract

Irradiation of InN films with 2MeV He+ ions followed by thermal annealing below 500°C creates films with high electron concentrations and mobilities, as well as strong photoluminescence. Calculations show that electron mobility in irradiated samples is limited by triply charged donor defects. Subsequent thermal annealing removes a fraction of the defects, decreasing the electron concentration. There is a large increase in electron mobility upon annealing; the mobilities approach those of the as-grown films, which have 10 to 100 times smaller electron concentrations. Spatial ordering of the triply charged defects is suggested to cause the unusual increase in electron mobility.

Identifying vacancy complexes in compound semiconductors with positron annihilation spectroscopy: A case study of InN

“…Indium 4d electrons are included as valence electrons and an energy cutoff of 400 eV is chosen. The Brillouin zone is sampled with a 3 3 Monkhorst-Pack k-point mesh.…”

“…2 Intrinsic point defects have been accounted for multiple important mechanisms in the material. [3][4][5][6][7] Among them, isolated and complexed In vacancies (V In ) and N vacancies (V N ) are expected to be the dominant intrinsic acceptors and donors, respectively, according to latest density functional theory calculations. [8][9][10][11][12] Nevertheless, unambiguous experimental evidence on their nature and characteristics is still relatively scarce.…”

Defect evolution and interplay in n-type InN

“…4 Additionally, high densities of extended defects are commonly found in as-grown material and have been correlated with an electron accumulation layer at InN interfaces. 5 In this letter, we use positron annihilation spectroscopy (PAS) and transmission electron microscopy (TEM) to study the evolution and interplay of native point and extended defects in highly n- He þ ions at a fluence of 8:9 Â 10 15 cm À2 and subsequently rapid-thermal-annealed (RTA) at 475 C. 6 All films were deposited by plasmaassisted molecular beam epitaxy (PAMBE) as $500 nm thick layers on c-plane sapphire substrates with a GaN buffer layer. 6,7 TEM measurements of thin cross-sectional samples were performed using a JEOL 2010 operating at an acceleration voltage of 200 kV.…”

Self-compensation in highly n-type InN

“…At moderate doping levels, the mobility data of the Sidoped samples are fitted well by calculated mobilities using A ¼ 0.33. As-irradiated films 16 show much lower mobilities and are approximated best with A ¼ 0.14. After RTA treatment, the mobilities in the irradiated films are close to the values for the Si-doped samples.…”

“…Although, for example, Hall measurements can give indirect evidence of defect charge and concentrations, 8,9,[15][16][17] defect identification is mostly not possible. Positron annihilation spectroscopy is a powerful tool for the investigation of vacancies and acceptor-type defects in semiconductors and is largely not affected by aforementioned properties.…”