Stress evolution during metalorganic chemical vapor deposition of GaN

Abstract

The evolution of stress in gallium nitride films on sapphire has been measured in real time during metalorganic chemical vapor deposition. In spite of the 16% compressive lattice mismatch of GaN to sapphire, we find that GaN consistently grows in tension at 1050 °C. Furthermore, in situ stress monitoring indicates that there is no measurable relaxation of the tensile growth stress during annealing or thermal cycling.

Characterization of low-frequency noise in molecular beam epitaxy-grown GaN epilayers deposited on double buffer layers

“…2, the PL peak positions are 3.413, 3.412, and 3.418 eV for samples I, II, and III, respectively, indicating that sample III suffers from a large compressive stress compared to samples I and II. It was shown by Hearne et al 27 that for GaN films grown pseudomorphically under tensile stress on sapphire substrates, the plastic deformation in the films is negligible during postgrowth cooling and dislocations in GaN have low mobility so that the dislocations freeze out after the epitaxial growth. 28 Due to the difference in thermal expansion coefficients between sapphire and GaN, it is postulated that larger compressive stress measured at room temperature corresponds to a lower tensile stress at the growth temperature as shown in Fig.…”

Изменение характера биаксиальных напряжений при возрастании x от 0 до 0.7 в слоях Al-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N:Si, полученных методом аммиачной молекулярно-лучевой эпитаксии

“…2. В [17] найдено, что перестройки дефектной (дислокационной) структуры при охлаждении не происходит, т. е. нет релаксации напряжений роста при охлаждении. Это позволило оценить напряжения после окончания роста (ростовые) σ grow для интервала x = 0−0.7.…”

High Al-Content AlInGaN Devices for Next Generation Electronic and Optoelectronic Applications

“…In-situ stress/strain monitoring was conducted during the growth of a similar MQW structure and is shown in Figure 19. While the GaN layer is under tension [49] during growth (0.40 GPa), the AlGaInN/GaInN MQW region is under compression during growth (~0.47±0.07 GPa). Assuming a compressive thermal mismatch stress of 0.2 GPa from 1050°C to 800°C, one can estimate an average compressive mismatch strain of 0.15%, corresponding to the lattice constant of a 1.4% GaInN epilayer.…”

“…Changes in wafer curvature induce a proportional change in the beam spacing on the camera. This technique provides a direct measurement of the stress-thickness product during MOVPE of GaN [49]. In attempting to extract band gap energy from a PL measurement for the AlGaInN quaternary system, one is reminded that the determination of band gap energy for GaInN has been a subject of much debate [50].…”

“…Details of the experimental setup and analysis of the stress evolution of GaN films are provided in Ref. [8], with a general description of the MOSS technique given in Ref. [9].…”