Decomposition Mechanisms of Di-tert-butylaminoarsane (DTBAA)

Abstract

III−V semiconductors containing small amounts of nitrogen ("dilute nitrides") are very promising material systems for optoelectronic applications. Devices based on dilute nitrides currently suffer from problematic C incorporation. To overcome this problem, a novel nitrogen (N) and arsenic (As) precursor for metal−organic vapor phase epitaxy (MOVPE) of the dilute nitride di-tertbutylaminoarsane (DTBAA) has been introduced. DTBAA in comparison to the commonly used 1,1-dimethylhydrazine (UDMHy) showed a significantly improved N incorporation efficiency. The molecule exhibits no strong carbon (C)−N bond, and the C is only present in large alkyl groups which form fewer C radicals since β-H elimination is the dominating decomposition process. This should significantly lower the problematic C incorporation in dilute nitrides and lead to highly efficient devices. To understand the high N incorporation efficiency as well as the As incorporation, the gas-phase decomposition of this novel precursor has been studied with a real time Fourier transform (FT) quadrupole ion trap mass spectrometer (iTrap) from Carl Zeiss SMT GmbH in a horizontal Aixtron Aix 200 GFR MOVPE reactor. Formation of isobutane and isobutene proves a radical cleavage and β-H-elimination as decomposition processes of the tert-butyl groups attached to the molecule. Furthermore, the appearance of ammonia (NH 3 ) has been detected. This indicates a direct cleavage of the As−N bond of the molecule, resulting in the formation of an aminyl radical (NH 2• ). The formation of NH 2 • explains the high N incorporation efficiency of DTBAA as well as its limitations due to desorption of NH 3 at higher temperatures.

2,6‐Diisopropylphenyl‐Substituted Bismuth Compounds: Synthesis, Structure, and Reactivity

“…[22] Recently, we showed that interpnictogen compounds are useful as precursors for the preparation of doped semiconductors via MOCVD processes. [27][28][29][30][31] Using aryl substituents at bismuth, could give access to interpnictogen compounds that prove useful as precursors.…”

Ga(N,P) Growth on Si and Decomposition Studies of the N–P Precursor Di-tert-butylaminophosphane (DTBAP)

“…These reaction pathways have been predicted by density functional theory calculations for the As analogue DTBAA and are on the one hand shown in decomposition studies of this precursor. On the other hand these pathways are also known for other metal–organic precursors with tert -butyl groups such as TBAs. ,, Another expected reaction pathway of the tert -butyl groups is decomposition through β-H elimination. In this case a H atom at one of the C atoms in a β position within the tert -butyl group interacts with the p orbitals of the phosphorus atom of the same molecule.…”

“…Additionally, NH 3 was detected with the same intensity as that for DTBAP. The detected NH 3 is attributed to the formation of aminyl radicals (NH 2 • 16 u) during the decomposition of DTBAP and was also observed as a decomposition product of DTBAA . This indicates a radical decomposition of the N–P bond of the molecule, which leads to the formation of NH 2 • and DTBP • (145 u).…”

“…To study the thermal decomposition of DTBAP, a quadrupole ion trap mass spectrometer from Carl Zeiss GmbH (iTrap) was used in line with the MOVPE system. The setup is designed to achieve measurement conditions as close to realistic growth conditions as possible and has been successfully used for gas-phase investigations of tert- butylarsane (TBAs) and DTBAA before. , The ion trap uses standard electron impact ionization with 70 eV for ion generation. The ions were then captured by an oscillating electric field applied to the ring electrode of the ion trap.…”

“…A novel arsenic (As)- and N-containing precursor (di -tert- butylaminoarsane, DTBAA) for the growth of GaAs-based dilute nitrides was investigated in the last few years and showed a high N incorporation in Ga­(N,As), (Ga,In)­(N,As), and Ga­(N,As,Sb) and a low decomposition temperature. − On the basis of the experience with this precursor a similar N- and phosphorus (P)-containing precursor (di -tert- butylaminophosphane, DTBAP) was synthesized and tested in the function of a precursor for MOVPE.…”