Properties of Si-Doped a-Plane GaN Grown with Different SiH₄ Flow Rates

Abstract

Nonpolar Si-doped a-plane GaN layers were grown using metal organic chemical vapor deposition (MOCVD) with different silane (SiH 4 ) flow rates. The on-axis full width at half maximum (FWHM) of X-ray rocking curves (XRCs) along the c-and m-axis directions showed that Si doping barely affected the anisotropy of a-plane GaN. A decrease in the edge threading dislocations (TDs) with increasing Si doping was confirmed by the decreased off-axis FWHM values of the XRCs. With increasing SiH 4 flow rate, both the carrier concentration and mobility increased through a reduction in the edge dislocation density. The photoluminescence (PL) spectra revealed that the PL peak positions were first slightly redshifted and then blueshifted with increasing carrier concentration. #

Mg Doping Effect in Nonpolar a-Plane GaN

“…Figure 1 shows both the hole concentration and mobility of Mg-doped a-plane GaN with different Cp 2 Mg flow rates. As previously reported, 12) undoped GaN is highly resistive, probably due to many acceptor-like defects that act as compensation centers. 13) With increasing Cp 2 Mg flow rate, the hole concentration initially increased from 4:58 ðAE0:62Þ Â 10 17 to 7:88 ðAE0:48Þ Â 10 17 cm À3 .…”

Ge as a surfactant in metal-organic vapor phase epitaxy growth of a-plane GaN exceeding carrier concentrations of 1020 cm−3

“…However, silicon-induced structural degradation for electron concentrations n > 1 Â 10 19 cm À3 limits the utilizable doping range. 4 The very promising results recently achieved for c-plane GaN suggest that the use of Ge might be one of the alternatives to overcome these problems. Dadgar et al studied the influence of Si and Ge doping on strain evolution in c-plane GaN grown by metal-organic vapor phase epitaxy (MOVPE) on Si substrates and found crack formation using Si doping levels already below 1 Â 10 19 cm À3 , while Ge doping even above 1 Â 10 19 cm À3 did not lead to cracks or tensile stress.…”

“…Such 3D-2D transitions were found to be beneficial to grow pit-free a-plane GaN films with good crystal quality. 4,7,8 Finally, an about 1:4 lm thick Si or Ge doped GaN top layer was grown at 1125 C and 100 mbar to maintain 2D growth and avoid hillock formation. For this layer the molar flow rates of the precursors trimethylgallium (TMGa) and ammonia were kept constant at 100 lmol=min and 22 mmol/min, respectively.…”

A Comparative Study on the Optical and Electrical Properties of Si-Doped Polar and Nonpolar GaN

“…This was followed by the growth of an approximately 3-m-thick GaN layer using a two-growth scheme. 14) Then, $3-m-thick Si-doped GaN films were grown on both the c-and a-plane undoped GaN films. The Si-doped c-and a-plane GaN films were designed to have the same electron concentration for systematic comparison.…”