Auger Electron Spectroscopy of Aluminum Nitride Powder Surfaces

Abstract

The chemical states of powder surfaces depend on the manufacturing processes of the powders. The surface chemistry of three different commercial AIN powders, which are processed by carbothermal nitridation of Al2O3, chemical vapor deposition (CVD), and direct nitridation of aluminum, were evaluated by using Auger electron spectroscopy (AES). In order to obtain reference AES spectra of aluminum compounds, α‐, γ‐, θ‐Al2O3, γ‐AIOOH, γ‐AION, and sintered AIN were also examined. Line shapes of aluminum LVV; Al(LVV), nitrogen KLL; N(KLL) and oxygen KLL; O(KLL) are discussed for the AIN powders and all the other aluminum compounds. The differential Auger electron spectra, i.e., E dn/AE were obtained directly, where n is the number of Auger electrons, and E is the kinetic energy of the electron. Their integrated spectra, i.e., n(E) are also employed for analysis. The results confirm the conclusions of our previous temperature‐programmed desorption work. The AES line shape analysis implies the presence of an oxide‐like θ‐Al2O3 containing AION phase on the carbothermal nitride AIN powder surfaces. The surfaces of CVD and direct‐nitrided AIN powders are covered by an oxide–like γ‐Al2O3 with an oxygen diffusion layer and does not have AION phase.

Diffuse Reflectance Infrared Fourier Transform Spectroscopy of Commercial AlN Powders in Vacuum up to 700°C

“…Our present DRIFT analysis has revealed that the surface oxide of powders A and C possesses a boehmite‐like structure, and that of powder B is θ‐Al 2 O 3 like. This analysis has further confirmed and completed the previous TPD 20 and AES 21 studies, and is in agreement with the hydrolytic degradation–resistance properties observed recently 6,7 . In addition, the bands at 2245 and 2120 cm −1 observed above 200°C, which were not identified previously, might be assigned to OCN and CN groups, respectively, according to our analysis.…”

“…showed a much stronger one. A shoulder at 3765 cm −1 of the 3730 cm −1 band of powder B, although weak and with its intensity comparable with the noisy bands, could be due to the existence of Al IV –OH if the previous TPD 20 and AES 21 results are considered. In addition, in the carbothermal reduction and nitridation process, a postburning treatment at a moderate temperature (normally <1000°C) is usually necessary to remove residual carbon, and this could be the reason for the presence of θ‐Al 2 O 3 ‐like surface.…”

“…It should be noted here that the spectra of all three powders in the 1800–1000 cm −1 range (not shown) are very similar, at elevated temperatures showing only overtones or combinations of vibration modes of bulk AlN, and thus indicating that the absence of the Al IV –OH band in powder B is not due to the presence of remaining impurities like carbonates and carboxylates. Previous TPD and AES studies have showed a θ‐Al 2 O 3 ‐like surface for the powder produced via the carbothermal reduction and nitridation process, and γ‐Al 2 O 3 ‐ or AlOOH‐like surfaces for powders manufactured through CVD and direct nitridation processes 20,21 . The transition aluminas possess a spinal structure, where Al ions occupy both the tetrahedral and octahedral interstices in the array of O ions.…”

“…Unfortunately, few efforts have been directed toward differentiating AlN powder surfaces obtained via different processes. In our lab, temperature‐programed desorption (TPD) 20 and Auger electron spectroscopy (AES) 21 were performed to clarify surface differences of commercial AlN powders: comparison of AES spectra and desorption behavior of AlN powders with those of sintered AlN, sintered AlON, and various kinds of aluminum oxide powders (AlOOH, α‐, θ‐, and γ‐Al 2 O 3 ) indicated a θ‐Al 2 O 3 ‐like surface for the powder produced via the carbothermal reduction and nitridation process, and γ‐Al 2 O 3 ‐ or AlOOH‐like surfaces for powders manufactured through CVD and direct nitridation of aluminum processes 20,21 . On the other hand, in the investigation of the surface change during storage over years using XPS analysis, Kameshima et al 22 .…”

The Hydrolysis of AlN Powder – A Powerful Tool in Advanced Materials Engineering

“…The higher the content of oxygen, the higher was the length of the initial stage. According to an auger electron spectroscopy (AES) study of AlN powder surfaces, the chemical states of the powder surfaces depend on the manufacturing processes for the preparation of the powders . The AES analysis indicated the presence of an oxide‐like‐Al 2 O 3 containing an AlON phase on the surface of AlN powder prepared by the carbothermal‐nitridation process, while those prepared by CVD and the direct‐nitridation method are covered by an oxide‐like‐Al 2 O 3 with an oxygen diffusion layer and do not contain the AlON phase.…”