Hot-Wall MOCVD for Highly Efficient and Uniform Growth of AlN

Abstract

We demonstrated successful growth of AlN at a temperature of 1200 °C in a set of hot-wall MOCVD systems with the possibility of straightforward scaling up the process on larger wafer areas to meet the demand of device technologies. We outlined several aspects of the carefully optimized design and process parameters with relevance to achievement of a high overall growth rate (1 and up to 2 μm/h), efficiency, and uniformity, which to a great extent depends on how consumption of growth-limiting species by gas-phase adduct formation can actively be prevented. Mixing of the precursors upstream from the deposition area facilitates uniform epitaxial growth, while the greater uniformity of substrate temperature inherent to the hot-wall reactor and rotation of the wafer are of fundamental importance for layer-growth uniformity. The AlN layer thickness can be controlled with an accuracy of ±1.3% on 2 in. wafers. The low-temperature cathodoluminescence spectrum of the AlN epitaxial material is strongly dominated by the intense near band-gap deep UV emission at about 208 nm.

High-quality AlN layers grown by hot-wall MOCVD at reduced temperatures

“…The substrate is heated by physical contact with the RF-heated susceptor and the additional radiative heating from the susceptor surfaces. The flow rates of carrier gases, H 2 and N 2 , were optimized for high efficiency and uniformity of the AlN growth on 2" SiC wafers [8]. The SiC substrates used in this study were of the 4H polytype and nominally on-axis.…”

“…In this paper, we discuss surface morphology and CL of AlN epitaxial layers grown in a horizontal-tube hot-wall MOCVD reactor configured for operation at temperatures of up to 1500-1600 o C [8]. Here we report on a growth of AlN at reduced temperatures of 1100 o C and 1200 o C, which are the maximal attainable by most of the present MOCVD systems.…”

Impact of residual carbon on two-dimensional electron gas properties in AlxGa1−xN/GaN heterostructure

“…This may determine how low carbon incorporation can be obtained in the process. Thanks to the high precursor cracking efficiency in hot-wall MOCVD, 15 this renders remarkably large carbon tuneability in GaN growth by more than 2 orders over a temperature range of 100 C. Besides, in the sample S1, the silicon concentration in GaN is below the SIMS detection Fig. 1(b), the growth temperature, as monitored by a pyrometer, is also shown.…”

“…12,15 The growth was initiated with an AlN nucleation layer (100 nm thick) grown at 1100 C after SiC substrate surface pretreatment in H 2 ambient at 1200 C for 15 min, followed by GaN growth or AlGaN/GaN HEMT structure growth. Two samples of GaN layers on AlN/SiC system were grown under a constant NH 3 flow (2 l/min), denoted S1 and S2, to study the residual impurity incorporation in GaN as a function of its growth conditions.…”

Electron effective mass in Al0.72Ga0.28N alloys determined by mid-infrared optical Hall effect

“…22 A graded buffer layer structure, consisting of an undoped AlN layer, a continuously graded AlGaN layer, and an undoped Al 0.72 Ga 0.28 N layer, is used for strain engineering in order to avoid cracking. Further details on growth conditions and structural analysis can be found in Ref.…”