Nanometer scale composition study of MBE grown BGaN performed by atom probe tomography

Abstract

Laser assisted atom probe tomography is used to characterize the alloy distribution in BGaN. The effect of the evaporation conditions applied on the atom probe specimens on the mass spectrum and the quantification of the III site atoms is first evaluated. The evolution of the Ga++/Ga+ charge state ratio is used to monitor the strength of the applied field. Experiments revealed that applying high electric fields on the specimen results in the loss of gallium atoms, leading to the over-estimation of boron concentration. Moreover, spatial analysis of the surface field revealed a significant loss of atoms at the center of the specimen where high fields are applied. A good agreement between X-ray diffraction and atom probe tomography concentration measurements is obtained when low fields are applied on the tip. A random distribution of boron in the BGaN layer grown by molecular beam epitaxy is obtained by performing accurate and site specific statistical distribution analysis.

Correlative investigation of Mg doping in GaN layers grown at different temperatures by atom probe tomography and off-axis electron holography

“…44 Precedent studies reveal that such field conditions lead measuring a more reliable III-fraction in ternary GaN-based alloys. 15,16,26 This consideration can also be extended to the case of MgGaN, even if a dedicated study have yet to be developed. Therefore, only information from doped layer grown at T growth = 1010 • C to the doped layer grown at T growth = 1090 • C are extracted and compared relatively.…”

“…Of course, the measured fraction y within a layers is not strictly quantitative and is only used to demonstrate the relative evolution of the composition. 15,16,26 The Mg fraction for both the potentially active Mg atoms in p-doped layers and those detected in the NID layers is shown in Figure 3 Off-axis electron holography technique is a TEM based technique that uses an electron biprism to create an interference pattern known as the hologram. 27 A coherent electron wave that passes through the specimen is interfered with another that passes through vacuum.…”

Behavior of the ε-Ga2O3:Sn Evaporation During Laser-Assisted Atom Probe Tomography

“…This is a challenge for APT because doping concentrations are generally just one or two order of magnitudes higher than the detection limit of the technique and accurate quantifications are also affected by the presence of compositional biases. The same approach adopted to study the metallic content in ternary alloys (Bonef et al, 2017; Di Russo et al, 2018 a , 2018 b ; Di Russo et al, 2019) was then extended to determine the field dependence (i.e., as a function of the Ga-CSR) of the detected Sn-metallic fraction y in ε-Ga 2 O 3 :Sn. This last quantity is defined as it follows:where N Sn and N Ga are the number of detected Sn and Ga atoms, respectively.…”

Multi-microscopy nanoscale characterization of the doping profile in a hybrid Mg/Ge-doped tunnel junction

“…The choice for the mass spectrum peak indexing is the same as the one commonly reported in literature [34][35][36][37][38][39][40][41][42][43][44]. Mg 2+ cations are associated with the peaks at 12, 12.5 and 13 Da, due to its three isotopes ( fig.…”