Fig. 4: Growth mode phase diagram of gallium selenide growth as a function of T_sub and Φ_Se/Ga.

The predominant growth modes and crystalline phases are represented by color-coded growth regimes: yellow (3D-nanoflakes gallium selenide, predominantly 1:1 stoichiometry), red (Ga₂Se₃, 2:3 stoichiometry), light blue (Ga droplets), green with blue checks (clusters with GaSe underlayer), green (clusters with no underlayer), blue (2D GaSe growth), and white/gray (desorption or no growth). Data points with error bars represent the experimentally measured boundaries between growth modes (the error bars correspond to the estimated uncertainties in the calibration of temperature and flux variations across the wafer). Solid lines are Arrhenius fits corresponding to the experimentally derived boundaries. The boundaries defined by the red and dark gray markers are based on correlations between SEM and optical images. The transition extracted from the blue triangles is derived from SEM-based cluster density and footprint area measurements (see Fig. 2).