Atom probe tomography study of Mg-doped GaN layers

Abstract

Atom probe tomography studies on highly Mg-doped homoepitaxial GaN (0001) layers with concentrations of 5 × 10(19) cm(-3) and 1 × 10(20) cm(-3) were performed. Mg cluster formation was observed only in the higher doped sample whereas in the lower doped sample the Mg distribution was homogeneous. CL measurements have shown that the emission normally attributed to stacking faults was only present in the lower doped layers (with Mg concentration of ∼5 × 10(19) cm(-3) or less), but absent in the higher doped layer, where Mg clusters were detected. Mg clusters are proposed to produce a screening effect, thereby destroying the exciton binding on the SFs and thus rendering them optically inactive.

Laser-assisted atom probe tomography of 15N-enriched nitride thin films for analysis of nitrogen distribution in silicon-based structure

“…2 and 3 was due to molecular ion N 2 + . This tendency is similar to that seen in previously reported results of films including nitrogen, such as SiON [4], GaN [8][9][10][11] and TiAlN [12], whereas O + , not O 2 + , was the largest contribution to oxygen counts of SiO 2 [5]. Fig.…”

Hillock assisted p-type enhancement in N-polar GaN:Mg films grown by MOCVD

“…Density functional theory calculations suggest a lower stress for Mg atoms incorporated at step edges of the semi-polar (1011) GaN 38 which may lead to reducing the formation of V N , that act as compensating donors 19 . The increased hole concentration of GaN:Mg films grown on HHT is attributed to the increased substitutional Mg incorporation at electrically active Ga sites, decreased Mg incorporation into clusters, and a decreased formation of compensating defects 20,37,38 .…”

“…Mg is the most common p-type dopant in the III-nitride material system due in part to an established activation process 18 . However, challenges remain to obtaining high conductivity p-type films utilizing Mg as the dopant due to a high ionization energy, the formation of compensating nitrogen vacancies 19 , and segregation of Mg into clusters that may be electrically inactive 20 . Additionally, the N-polarity suffers from a high concentration of unintentionally incorporated oxygen (compared to the Ga-polarity), which compensates free holes 21 .…”

“…Atomic size, valency and electronegativity are among the factors determining the solid solubility of a dopant in a material 33 . Mg has been shown in Ga-polar GaN grown by MOCVD to form clusters at high dopant concentrations above 1 × 10 19 cm −3 , which have been shown to impact the optical properties of the film 20 . In addition to Mg, Manganese (Mn) doping in GaN grown by MBE has been studied for ferromagnetic properties in spintronic applications and has been shown to form clusters 34,35 .…”

Effect of dislocations on the growth of p-type GaN and on the characteristics of p-n diodes

“…However, the hole concentration drops if the doping density of Mg is above 10 19 cm −3 , thereby complicating the production of p‐GaN with a high hole concentration. Numerous studies have attributed this drop in hole concentration variously to hydrogen passivation (Mg‐H) , self‐compensation by nitrogen vacancy ( V N ) , interstitial Mg (Mg inter ) , and Mg segregation . However, despite these previous efforts, the actual mechanism remains unclear.…”