Cathodoluminescence imaging for the determination of dislocation density in differently doped HVPE GaN

Correlation between structural properties and nonradiative recombination behaviors of threading dislocations in freestanding GaN substrates grown by hydride vapor phase epitaxy

“…Our results for the pit size and its correspondence with the Burgers vector conflict with the size ranking of screw>mixed>edge in some publications where only KOH or a mixture of KOH and NaOH was used. 14,16,19,57,58 The geometric features of etch pits in our study are also different from those formed by KOH 54 or HCl gas. 28 In these reports, the etch pits corresponding to TMDs have two-step facets, which appear as a combination of triangular and trapezoidal shapes when viewed along the cross-sectional direction.…”

“…Atomic force microscopy (AFM) measurements showed that the as-grown surface was covered with atomic steps, which indicates a two-dimensional (2D) stepflow growth. The HVPE-grown layer was nominally undoped, and the impurity concentrations as measured from secondary ion mass spectrometry (SIMS) were [C]=2×10 16 cm -3 , [O]=3×10 16 cm -3 , and [Si]=5×10 15 cm -3 .…”

“…Meissner et al 16 studied an Fe-doped FS-GaN layer and Sidoped GaN films grown via HVPE using CL and the etch pit method. They confirmed a one-to-one correlation between the CL dark spots and the etch pits, but there was no direct relationship between the pit size and the contrast of the respective dark spot.…”

“…Henceforth, we refer to the 1a, 1c, and a+c dislocations as TED, TSD, and TMD, respectively, unless specified otherwise. The TDs have deleterious effects on the performance and lifetime of GaN-based devices through mechanisms such as carrier scattering, 9,10 carrier trapping via nonradiative recombination (NRR), [11][12][13][14][15][16] and paths for leakage current. [17][18][19][20][21][22] These different mechanisms are connected by the fact that dislocations act as one-dimensional (1D) charged defects that introduce electronic states into the energy gap.…”

Growth of High‐Quality AlN and AlGaN Films on Sputtered AlN/Sapphire Templates via High‐Temperature Annealing

“…High‐AlN mole fraction AlGaN without AlN regrowth was also determined from the CL measurement results, in which the dark spot density related to the dislocations was calculated to be 1.23 × 10 9 cm −2 . In the calculation of dislocation density, the number of dark spots of CL‐image considered to be due to dislocation was counted and the density per area was calculated …”