Attractive electron mobility in (113) n-type phosphorus-doped homoepitaxial diamond

Abstract

A (113) diamond homoepilayer doped with phosphorus is grown. It presents high crystalline quality and n-type conductivity with a maximum electron mobility of 355 cm²/V.s at 450K. Its electrical properties are compared to those measured on conventionally oriented (100) and (111) homoepilayers synthetized in the same reactor with similar phosphorus content (~1-2x10 18 /cm 3 ). The (113) layer presents higher electron mobility than the (100) film, despite a comparable compensation ratio. Besides, above 450K the (113) electron mobility is also higher than the one of the low compensated (111) sample. This shows the attractive character of the (113) diamond orientation for n-type doping. high temperature power electronics. Compared to other wide bandgap semiconductors (ex: ZnO and GaN), high mobility of the holes is a prime advantage for bipolar devices. However, diamond presents a doping asymmetry (as ZnO for example). While its p-type doping with boron in substitution for carbon is easy [2] [3] [4], its n-type conductivity is difficult to achieve. Being a major issue for the fabrication of diamond-based bipolar devices, n-type doping is an active research topic [5] [6] [7].Even if some incursions were made on the ( 110) orientation [8], the conventional crystalline orientations used for diamond are (111), that especially suffers from easy crystalline defect formation, and (100), on which better electronic properties are generally observed on larger surfaces [9]. Lying in between ( 111) and (100) [10], ( 113) is a stable growth orientation during chemical vapor deposition (CVD) [11] and could allow obtaining enlarged crystals [12]. The high potential of the ( 113) orientation was revealed recently thanks to the works of Lesik et al. [10] and Tallaire et al. [13]. For achieving a given film thickness together with a dedicated doping level, a wide growth window is a precious advantage. Tallaire et al. [13] show that the use of ( 113) orientation substrates for p-type boron doped diamond homoepitaxy allows extension of the optimal MPCVD growth window, compared to conventional (100) orientation (ex: higher growth temperatures and growth rates). Moreover, the (113) p-type doping has been reached with homoepilayers presenting high crystalline quality whatever the layer thicknesses, varying from a few hundred of micrometers to free-standing plates. No unepitaxial defects (as crystallites) were observed unlike on (100) orientation. A freestanding plate of (113) heavily boron doped CVD diamond exhibits low resistivity compared to (100) orientation. Even if heavily boron doped diamond is reached on (111) orientation substrates, the formation of twins and growth defects forbidden the growth of thick high boron doped (111) layers. Thus, compare to (100) and (111) orientations, it is possible to consider highly conductive (113) substrates that are required, for example, in vertical Schottky diodes. By improving boron doping efficiency in high-quality thick diamond, (113) orientation could represent a good tradeoff between (100)...

Nitrogen Investigation by SIMS in Two Wide Band-Gap Semiconductors: Diamond and Silicon Carbide

“…The detected masses are usually the one coming from the matrix elements of the homoepilayer (as 12 C) and the one coming from the expected impurities that are also contained in the homoepilayer (as the dopants 11 B or 31 P [10,11]).…”

Diamond for Electronics: Materials, Processing and Devices

“…This structure is anisotropic and results in high dependence with the plane of growth for growth rates, impurities incorporation, and surface passivation. This particularity has been used by authors for growth along unusual orientations for applications such as defects reductions [65,66] or doping optimization [67]. More recently, the anisotropy of diamond has been considered as an advantage for the design of three-dimensional architectures for devices that contributes to overcome the classical issues in diamond technology.…”

“…The problems of n-type layers are still not fully solved. However, today, n-type doping level is possible to control from 10 15 -10 20 cm −3 , and then significant reduction in resistivity by using hopping conduction has been reported in the pin structure [149], and improvement in the crystal quality of phosphorus-doped (n-type) diamond has been reported [67,174]. As a summary, diamond devices still have many issues for practical use; however, considering the remarkable development in recent years, ultra-high-power diamond devices can be achieved both for HVDC and RF applications in the near future.…”

UV Light Irradiation Effects in P-Doped Diamonds: Total Content Determination of Phosphorus Donors

“…For decades, diamond was considered to be a typical insulator due to the difficulties in doping it caused by electroactive impurities to control its conductivity. However, with the development of synthetic growth methods, such as the high-pressure high-temperature (HPHT) gradient one [3][4][5][6][7][8][9] and chemical vapor deposition (CVD) [10][11][12][13][14][15][16][17][18][19][20][21], it became possible to manage the content of impurities and the electrical properties of diamonds.…”

“…Boron-doped p-type diamonds are fairly easy to produce [3][4][5][6][10][11][12]. However, for solid state physics and for the development of quantum computers, n-type diamonds doped with phosphorus are demanded [7][8][9][13][14][15][16][17][18][19][20][21]. The boron (B) acceptor level of 0.37 eV above the valence band maximum and the phosphorus (P) donor level of 0.6 eV below the conduction band minimum are formed with the substitutional B or P incorporation into the diamond lattice.…”