Details

Autor(en) / Beteiligte

• Hertkorn, J.
• Brückner, P.
• Thapa, S.B.
• Wunderer, T.
• Scholz, F.
• Feneberg, M.
• Thonke, K.
• Sauer, R.
• Beer, M.
• Zweck, J.

Titel

Optimization of nucleation and buffer layer growth for improved GaN quality

Ist Teil von

• Journal of crystal growth, 2007-10, Vol.308 (1), p.30-36

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2007

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• By accurately optimizing the growth conditions for an oxygen doped AlN nucleation layer and for the subsequent epitaxial process the crystal quality of our GaN layers could be improved drastically. In X-ray diffraction analyses we observed FWHM values of 39 and 114 arcsec for the symmetric (0 0 4)- and asymmetric (1 1 4)-reflection, respectively. Consequently, the nominally undoped samples showed semi-insulating behavior in Hall measurements. By in situ deposition of a SiN interlayer, the dislocation density could be reduced by more than a factor of 2, reaching a value of 4 × 10 8 cm - 2 as confirmed by transmission electron microscopy and etch pit density counting. Samples with this low dislocation density showed an extremely narrow X-ray FWHM of 71 arcsec for the asymmetric (1 1 4)-reflection along with a narrow linewidth of 870 μ eV in photoluminescence (PL) for the donor bound exciton (D 0 X) at a temperature of 10 K. Atomic force microscopy yielded a very low rms roughness value of about 0.14 nm across a 4 μ m 2 scan area. Finally the excellent crystal quality could be confirmed by growing AlGaN/AlN/GaN high electron mobility transistor structures with reverse breakdown voltages ⩾ 1000 V and a very low sheet resistance of 330 Ω / □ .