In situ metrology advances in MOCVD growth of GaN-based materials

Growth optimization during III-nitride multiwafer MOVPE using real-time curvature, reflectance and true temperature measurements

“…The thin nucleation layer does not result in any resolvable change in curvature. Reported values of approximately 2 km À1 curvature change for a 28 nm thin GaN nucleation layer [15] are below our resolution limit.…”

Emissivity-correcting near-UV pyrometry for group-III nitride OMVPE

“…Various methods of emissivity measurement and correction can be applied to improve the utility and accuracy of pyrometry. In fact, EC or emissivitycompensation is almost always necessary due to the optical interference effects that occur during heteroepitaxy [14][15][16]24,25]. The emissivity for an opaque material is simply given by e ¼ 1ÀR [24], so the standard approach is to measure the reflectance (R) at the same angle and polarization as the thermal emission signal.…”

“…900-1000 nm) normally used for pyrometry [14][15][16]. One solution would be to detect radiation near the GaN bandgap where the GaN epilayer templates are opaque.…”

Emissivity-correcting mid-infrared pyrometry for group-III nitride MOCVD temperature measurement and control

“…Emissivity correction or emissivity compensation is almost always necessary due to the optical interference effects that occur during heteroepitaxy [25,26,31,32]. The emissivity for an opaque material is simply given by e=1-R [31], so the standard approach is to measure the reflectance (R) at the same angle and polarization as the thermal emission signal.…”

“…900-1000 nm) normally used for pyrometry [25][26][27]. The problem is particularly severe because the InGaN composition (and therefore emission wavelength) is extremely sensitive to temperature in the 700-800 1C range, with a slope of $1-2 nm/1C [28].…”