Direct growth of cubic AlN and GaN on Si (001) with plasma‐assisted MBE

Abstract

Highly lattice mismatched (HM 2 ) heteroepitaxial growth of cubic zincblende c-AlN and c-GaN on Si (001) was performed by MBE using plasma excited nitrogen sources without using a low temperature buffer layer. The early stage of the direct nucleation of AlN and GaN on a Si substrate using microwave and radio frequency plasma-assisted MBE was studied. The islands of a zincblende structured material (c-SiN x [a = 0.43 nm]), effectively worked as a seed for successive coherent growth of c-AlN and c-GaN oriented 〈001〉. The growth of c-AlN and c-GaN was analyzed by reflection high energy electron diffraction, X-ray diffraction, and photoluminescence.1 Introduction Hybrid application of group III nitride semiconductors with silicon technology is a promising one for optical and electronic applications. The growth method of molecular beam epitaxy (MBE) is the most suitable one for interface flatness control and composition control of alloy crystals for optical and electronic applications. Although the hexagonal wurzite (W) phase (h-) of AlN and GaN is currently used for various applications, the cubic zincblende (ZB) (c-) phase is more attractive, because of the doping property and the similarity of the cubic system of Si technology for hybrid application. The growth of ZB group III nitrides by MBE was reported by using a low temperature buffer layer or surface pre-treatments of carbonization or nitridation for a Si substrate [1][2][3][4][5][6][7][8][9][10][11][12] and for other substrates [13 -20]. To overcome the problem of highly lattice mismatched (HM 2 ) hetero-epitaxial growth [21] is important for hybrid application. No direct growth of GaN from single crystal islands of silicon nitride (SiN x ) on Si(001) was reported before, except for the formation of amorphous SiN x at the GaN/Si interface [6][7][8]. The amorphous SiN x substrate operated as nucleation cores of h-GaN [7]. Single crystal islands work as coherent multi nuclei for the direct growth, which has merits to reduce the interface electric resistance for vertical devices and to reduce the process steps of device preparation. In this report the heteroepitaxial growth of ZB c-AlN and c-GaN on Si (001) will be performed by MBE without a low temperature buffer layer using nitrogen plasmas of microwave (µ-) and radiofrequency (rf-) discharges. Coherent growth for the single phase of cubic nitrides depending on plasma sources will be discussed.

Role of excited nitrogen species in the growth of GaN by RF–MBE

“…Therefore, plasma discharges are employed to produce excited nitrogen species such as nitrogen atoms (N), electrically excited nitrogen atoms (N * ), electrically excited nitrogen molecules ðN Ã 2 Þ and nitrogen ions ðN þ 2 Þ. Various techniques of plasma discharge including radio-frequency (RF) [1][2][3][4], microwave [5][6][7], electron cyclotron resonance of microwave plasma (m-ECR) [1,8,9], and DC plasma [10] have been proposed in MBE growth. Of these methods, the RF plasma method is commonly used for the MBE-growth of group III-nitride because RF plasma produces less N 2 + and more N and N * compared to m-ECR [1,11].…”

Control of nitrogen flux for growth of cubic GaN on 3C-SiC/Si by RF-MBE

“…The thickness of c-GaN was obtained using spectroscopic reflectometry with a Xe lamp and an Ag reference plate. The growth procedure is the same as reported elsewhere [2,11]. The thickness distribution was measured through interference color.…”

“…To increase the plasma excitation, the application of magnetic field in RF discharge is effective. The authors reported surface nitridation of Si to grow c-GaN [11]. They also improve the cubic substrate by carbonization using the alternating exposure method of Si and C 2 H 2 through a jet nozzle [2].…”

3C-SiC/Si template growth and atomic layer epitaxy of cubic GaN by RF-MBE

“…The Si substrates of S(0 0 1) and Si(1 1 1) were chemically etched with a solution of HF (5%):H 2 O (95%) for 1 min and then rinsed with deionized water before loading into the MBE [12]. A jet nozzle, in which 1 mm diameter hole was placed in the middle of a 5 cm long 1/4 in diameter stainless-steel tube to produce jet flow, was used to carbonize the surface of a Si substrate under UHV with the alternating exposure of C 2 H 2 and Si flux.…”