MBE growth of nitride-based photovoltaic intersubband detectors

Abstract

In this work, we present the plasma-assisted molecular-beam epitaxial growth of quantum well infrared photodetector (QWIP) structures, including the Si-doped GaN/AlN short-period superlattice of the active region, conductive AlGaN claddings and integration of the final device. The growth of Si-doped GaN/AlN multiple quantum well (QW) structures is optimized by controlling substrate temperature, metal excess and growth interruptions. Structural characterization confirms a reduction of the interface roughness to the monolayer scale. P-polarized intersubband absorption peaks covering the 1.33-1.91 µm wavelength range are measured on samples with QW thickness varying from 1 to 2.5 nm. The absorption exhibits Lorentzian shape with a line width around 100 meV in QWs doped 5 × 10 19 cm −3 . To prevent partial depletion of the QWs owing to the internal electric field, we have developed highly-conductive Si-doped AlGaN cladding layers using In as a surfactant during growth. Complete ISB photodetectors with 40 periods of 1 nm-thick Si-doped GaN QWs with 2 nm-thick AlN barriers have been grown on conductive AlGaN claddings, the Al mole fraction of the cladding matching the average Al content of the active region. Temperature-dependent photovoltage measurements reveal a narrow (∼90 meV) detection peak at 1.39 µm.

Progress in Symmetric and Asymmetric Superlattice Quantum Well Infrared Photodetectors

“…A III‐nitride photodetector covering the 1.33–1.91 μm range has been already proposed . This range overlaps the mentioned “forbidden gap” and covers part of the SWIR.…”

Synthesis of (Hf, Zr)B2-based heterostructures: hybrid substrate systems for low temperature Al–Ga–N integration with Si

“…In this case, since the Al-N bond is significantly stronger than its Ga-N counterpart, the liberated Ga can diffuse on the surface and function as a surfactant to promote an organized assembly of the growing film. 14,15 The displaced Ga eventually evaporates from the growth front into the vacuum owing to its high vapor pressure at the deposition conditions of 10 À7 Torr and 700 C.…”

Ternary AlGaN Alloys with High Al Content and Enhanced Compositional Homogeneity Grown by Plasma-Assisted Molecular Beam Epitaxy

“…scans on symmetric 0002 reflection for two samples: one grown in N-rich growth conditions due to high growth temperature at 760 C, the other one at optimized growth conditions (T S ¼ 670 C), as well as values from literature. [24][25][26][27][28][29] It has to be noticed that crystalline quality as measured by HRXRD is strongly dependent on the quality of the substrate, the strain state and the growth method used.…”