3results about How to "Improve epitaxy quality" patented technology

This invention provides a gallium arsenide triple-junction solar cell and its fabrication method, relating to the field of solar cell technology. It replaces the existing technology's self-forming Ge substrate with a low-cost N-type GaAs substrate and a thinner N-type Ge epitaxial layer. The thickness of the N-type Ge epitaxial layer ranges from 1 μm to 3 μm, reducing material costs by more than 40%. A two-step growth method is used to form a stacked low-temperature nucleation layer and a high-temperature host layer to form the N-type Ge epitaxial layer, which serves as the base cell of the gallium arsenide triple-junction solar cell. The epitaxial quality is high, with a dislocation density of the N-type Ge epitaxial layer less than or equal to 5 × 10⁻⁶. 6 cm ‑2 This effectively suppresses the problem of Ga / Ge interdiffusion; the photoelectric conversion efficiency of this gallium arsenide triple junction solar cell has been verified to be greater than 30%, which is comparable to the photoelectric conversion efficiency of gallium arsenide triple junction solar cells with Ge substrates forming their own bottom cells in existing technologies.

This invention relates to the field of semiconductor technology and discloses a surface planarization method for epitaxial group III nitride materials based on a 3D mask substrate. The method includes using an etchant to achieve anisotropic etching rate differences between the c, a, and m faces of the group III nitride material, thereby performing surface planarization on the epitaxially grown group III nitride material layer. The surface planarization process is a solution etching process. This invention only requires placing the epitaxial group III nitride material on the 3D mask substrate in a mixed solution of potassium hydroxide and sodium chloride or a mixed solution of phosphoric acid and sodium chloride under specific conditions for chemical wet etching. Sodium chloride can increase the etching rate difference between the horizontal and vertical surfaces of the uneven epitaxial GaN layer, while potassium hydroxide or phosphoric acid solutions will etch the protruding parts of the uneven epitaxial group III nitride material layer surface, making the GaN thickness uniform throughout the entire epitaxial wafer, thus achieving global planarization.

The application discloses an epitaxial equipment, which comprises a frame body, a transmission cavity, a gate valve, an adjusting assembly and a reaction cavity are arranged in the frame body, the transmission cavity is installed at one end of a support, the other end of the support away from the transmission cavity is fixed to the bottom of the frame body, and the transmission cavity is connected with the reaction cavity through the gate valve; the adjusting assembly is installed at the top of the frame body, and the adjusting assembly comprises a first connecting part and a guide rail assembly, the guide rail assembly comprises a guide rail and a slider matched with the guide rail, the slider is connected with the first connecting part, and the first connecting part is connected with the reaction cavity. Thus, the distance between the reaction cavity and the transmission cavity can be adjusted through the adjusting assembly, the operation space of the gate valve is sufficient during replacement and maintenance, and the efficiency of the gate valve maintenance and replacement is improved.